Grado Labs SR325x headphones

The Grado Prestige Series headphones have been around for quite a while, but of course they’ve been upgraded over the years. The latest upgrade, just out, is the “x” series. This consists of five models. Here I’ll be taking a close look at three of them, the entry level SR60x, the middle-of-the-range SR125x and the top-of-the-line SR325x. To place this in context, the Prestige Series is itself Grado’s entry level series of headphones. There are three other series above it in performance and price, as well as the occasional Limited Edition release, such as the Grado Hemp which I reviewed here.

tl;dr (applies to all unless otherwise stated)

  • On ear, open back headphones
  • Hand built in Brooklyn, New York
  • Fixed cables, 172cm, terminated with 3.5mm plug, 3.5mm to 6.35mm gold-plated adapter plug included
  • 44mm dynamic drivers
  • Nominal impedance: 32 ohms (according to packaging) or 38 ohms (according to Grado Labs web site)
  • Sensitivity: 99.8dB SPL for 1mW
  • Left and right drivers matched within: 0.1db (SR60x and SR125x); 0.05dB (SR325x)
  • Frequency response: 20-20,000 hertz (SR60x and SR125x); 18-24,000 hertz (SR325x)
  • Weight (my measurement, including cable and 6.35mm adaptor plug): SR60x, 242.6 grams; SR125x, 269.1 grams; SR325x, 351.5 grams
  • The Grado Labs SR60x headphones lean towards the midrange, providing detailed sound well beyond what you’d expect at this price point. Just don’t expect a whole lot of bass.
  • The Grado Labs SR125x headphones raise the ante on that, improving the bass noticeably, offering equally good value for money.
  • The Grado Labs SR325x headphones deliver a very substantial step up in overall performance, being solid all-rounders with a truly balanced and attractive sound.
  • Price: SR60x: $169; SR125x: $299; SR325x: $479
  • Available from fine audio retailers and direct from Addicted to Audio at these sites: SR60x, SR125x, SR325x
Grado Labs SR60x, SR125x and SR325x headphones

    More information the “x” headphones

    If you are familiar with Grado Labs’ on ear headphones, you’ll be completely familiar with the appearance of these three. They employ foam earpads – that on the SR325x is a ring with only a protective weave over the driver grille, while the other two are a couple of millimetres thick over the face of the driver. The earcups on the two lower-cost units appear to be constructed from ABS plastic, while the SR325x uses aluminium. Likewise, on the open back the two lower-cost units just have heavily perforated ABS plates to allow their drivers to breathe, while the SR325x uses a woven metal panel. The difference in weight is obvious in the hand, although all three sat lightly on my head.

    The two lower-cost headphones employ synthetic materials – vegan friendly, apparently – for the headband, while the SR325x uses nicely stitched leather. To be honest, I wouldn’t have been able to tell the difference between the two.

    And thank you, Grado Labs, for clearly marked left and right earcups. I hate having to puzzle over which way around to place headphones on my head.

    Grado Labs SR60x and SR325x headphones

    I understand that the drivers were redesigned for this “x” version of the Prestige range. All three use 44mm drivers. As we’ll see, the one in the SR325x seems quite different to the driver used in the other two. In any case, Grado Labs says that they all employ new voice coils and diaphragms “to further reduce distortion and enhance harmonic integrity”. That, it says, makes them easier for portable devices to drive.

    I found that they worked fine with portable devices – even a headphone adaptor on an iPhone 8 – thanks to their lowish impedance and their respectably high sensitivity.

    The cables have been redesigned to offer “more durability and flexibility”. The SR125x and SR325x cables use eight conductors, while the SR60x employs four.

    Does it mean anything that in the box the cable on the SR60x was bound up with a zip tie, which I had to cut, while the other two had the traditional reusable twist ties?

    Listening to music with the Grado SR60x headphones

    How you perceive the sound of any pair of headphones depends a great deal on what you’ve been recently listening with. Some reviewers seem – at least claim – to be capable of a kind of absolute objectivity. Not me. So I made the mistake initially of going straight from the SR325x headphones (which, as you’ll see, I really liked a lot) to the SR60x. And these were my notes:

    “Relatively pinched sound. Okay midrange, but it just lacks precision and extension. Nothing to the left and right on the frequency spectrum. Sorry, not nothing, just relatively little. The mids are good. The penetration of the congas/bongos/whatever on “Black Magic Woman/Gypsy Queen” from Abraxis was strong. It’s just without the solid bass underpinning. Yet, when Spinning Wheel kicks in, the bass guitar and kick drum make themselves known, with good grind on the bass in the middle section. So, extension and tonal balance compromised, but within that, dynamic delivery fully preserved.”

    Grado Labs SR60x headphones

    On re-reading, that first bit seems kind of harsh. So I’ve started again with these headphones as the first of the day. I’ll be using a small selection of the same tracks for all three headphones.

    The guitar on Dire Straits’ “Six Blade Knife” does indeed seem a little pinched at points, with slightly muted harmonics. The simple but powerful bass line is a touch recessed, but it’s certainly present. Advancing the volume makes it more accessible without the headphones seeming to strain at all due to the higher level. Very clean at comfortable to high listening levels.

    The synth drums at the start of Michael Jackson’s “Beat It” are thin and clicky. Are they always that way? The wires of the snare or “snare” (I’m not sure which), sit slightly above the mix, but that being an 80s song, perhaps it’s supposed to be that way. Except that the opening of “Killing in the Name” by Rage Against the Machine is also a bit bright and clicky. Only a little, but it’s noticeable. There’s also some unexpected sibilance in the vocals on that track. Generally good rhythmically and fairly tight control over the dynamics. The bottom frequencies of Bach’s Passacaglia and Fugue in C minor were entirely absent. I think even the 32 hertz first harmonic was just, just barely discernible.

    On Robben Ford’s “It’s My Own Fault” from Discovering the Blues, the powerful bass is considerably muted. Likewise for the kick. But, nicely, when I turn the thing up a lot louder, the kick comes in, remaining properly dullish, avoiding any distortion. There’s definitely a strong mid-range bias here, but a fine lack of significant distortion.

    Listening to music with the Grado SR125x headphones

    First, last night’s notes: “Switched over to these from the SR60x headphones mid-track in Supertramp’s Supertramp. Immediately an airier sound. Good kick drum on Robben Ford, Discovering the Blues, but bass a little recessed. Indeed, nice slam on kick. Handled the bass boost (hastily switched off) on the iFi ZEN CAN. Nice distance on cymbals on “Sweet Sixteen”. I confess: I was enjoying this so much I simply turned it up to a higher level, which of course brought up the level of the bass as well. Somehow it seemed more in balance once I’d done so.”

    This time, rather than switching instantly over from the SR60x, I went and did something else for half an hour before returning for some proper listening.

    Grado Labs SR125x headphones

    Upon returning, it was immediately obvious that the SR125x headphones deliver a more open, more cohesive sound. Bass is still a little recessed, but not as much as with the SR60x headphones. The synth drums and snare wires in “Beat it” are still there, and but have more body to them, making for a markedly smoother sound. The opening chords in “Killing in the Name” were still a touch bright for my taste, but with the addition of significant bass content, a real solidity underneath the performance, the whole piece snapped into proper focus. There was still some of that vocal sibilance, but this time more hinted at than fully realised. Whether due to the stronger bass or something else, the whole performance was tighter.

    A little to my surprise, there wasn’t much added to the deep bass in Passacaglia. The bass guitar in the Robben Ford was up little in level and once again, there was a more cohesive sense in the music. When I pushed the level up to bring up the kick drum and bass line a little more, Ford’s singing voice remained more relaxed than it had with the SR60x headphones.

    Obviously not perfect, but I could see myself enjoying a lot of music for a long time with the Grado Labs SR125x headphones. That’s not something I’d say about too many headphones in this price category.

    Listening to music with the Grado SR325x headphones

    I didn’t have much to say about the SR325x last night. Just: “Much more and deeper bass than SR125x. Seemed a little more sensitive too. Don’t even sound as though they’re in the same series.”

    And I meant that last sentence in a good way. A very good way. So let’s look at some specifics. On “Beat It”, all sense of the thinness was banished by the SR325x headphones. The snare wires are now part of the snare drum, contributing to its sound, not overpowering it. The driving bass is tight and controlled. And, yes, despite the official figures, these headphones are noticeably more sensitive than the other two.

    Grado Labs SR325x headphones

    “Killing in the Name” opens just the way it ought to sound, with powerful bass and a natural tonal balance. Vocal sibilance? None, despite the proliferation of Ss in the opening lyrics. Dynamic control was excellent.

    The bass was clearly more extended on the Passacaglia too, although I would have liked to see even more. The 32 hertz first harmonic was delivered, albeit at a slightly muted level. I doubt there was any of the 16 hertz fundamental. (I guess I’m being too demanding here, since my most recent experience of this piece, outside these Grado headphones, was with the Fostex TH-909 which is simply a standout in this regard, and costs around 400% more.)

    At last, the bass guitar on “It’s My Own Fault” was at roughly the right level, bold and bluesy. The kick drum gave a good, clean thump. And the cymbals now danced around the sound stage in my head, with a nice air and focus I didn’t notice in the other two headphones.

    Yes, the Grado SR325x are so much better than the other two, it is a little surprising that they are in the same series. And they are definitely headphones I could live with for a long, long time.

    Amplifier compatibility

    I plugged each of the headphones into my little test box, which places 466 ohms of resistance between each headphone channel and the amplifier. I plugged my test box into the output of the iFi ZEN CAN headphone amplifier – it’s capable of plenty of volts of output and negligible line resistance (0.55 ohms) Then I measured the frequency response of the signal being fed to each of the headphones. That signal is dependent at each frequency on the internal impedance of the headphones compared to the inline resistance from the amplifier. The impedance curve across the frequency spectrum of the headphones, as compared to the line resistance, is what determines the signal fed to the headphones. I explain all this here.

    Grado Labs SR60x and SR325x headphones

    The point of all this is to determine whether you can reasonably use these headphones with amplifiers with high levels of output impedance. Unfortunately, these are far from rare, yet they are rarely specified so you usually won’t know. Generally, home theatre receivers from the likes of Denon, Marantz and NAD have an output impedance in the region of 470 ohms (which is why I built my test box with a similar impedance). These graphs show the signal that will be fed to these headphones if powered by such devices. If you see a 6dB variation across the range, then you can expect a 0.6dB variation if the output impedance is around 50 ohms, and about 0.06dB of it’s five ohms.

    And if it’s 0.55 ohms, like the iFi ZEN CAN, and several other fine headphone amps, it’ll be just 0.006dB. That’s why I’m keen on the lowest possible internal impedance in a headphone amplifier.

    So, let’s see how these three headphones go. First, here is the measurement for all three headphones, with them sitting on my desk and neither their faces nor their backs limited in the transmission of sound:

    Grado Labs SR60x, SR125x and SR325x headphones with 466 ohms inline

    What we see is that there is a significant peak in the impedance of each of these headphones in the bass. For the SR60x it’s at around 100 hertz – and it boosts the signal by 9dB at that frequency. For the SR135x it’s at 90 hertz, and it boosts the signal by 9.5dB at that point. And the SR325x is boosting the signal by a huge 11dB at 80 hertz.

    But wait, there’s more! The impedance in a dynamic system like this depends in large part of the freedom of the parts to move. You don’t listen to headphones sitting on your desktop. You listen them on your head. That limits the freedom of the diaphragm to move, since there is a relatively small volume of air captured between the diaphragm and your head and ears, and that cushions it. That’s reflected in the system impedance.

    I put headphones on a lightly stuffed 165mm wide cardboard box to fake a head. Here’s the same measurement as above, but with each of the headphones so constrained:

    Grado Labs SR60x, SR125x and SR325x headphones with 466 ohms inline - closed

    All three headphones retain, as you can see, the frequency at which they have peak impedance. But for the SR60x and SR125x, the variation is reduced by between half and nearly a whole decibel. For the SR325x the result was substantially different. The variance fell from 11dB to 6.6dB. That was kind of surprising, so I repeated both open and closed measurements on the SR325x headphones again, and in both cases the curve overlaid the earlier measurement with effectively no variation whatsoever. So I guess the measurement was right.

    I had a quick listen to the SR125x headphones through the load box to assess the subjective sound. Lucky the ZEN CAN does have plenty of voltage (it can deliver nearly 7.5 volts into high impedances) because I needed a lot of it to get a decent volume out of these headphones. The result was a boosted mid-bass that initially dispelled any sense of bass lightness. If you’re not too fussy, you could use these on one of those high impedance receivers. But after a while I found it wearing since the bass that was being boosted wasn’t in the deficient frequencies, but in frequencies that were already being handled competently.


    All three of these headphones deliver real value for money. I guess I’ve been unkind to the Grado Labs SR60x headphones, but keep in mind their bargain price. The Grado Labs SR125x headphones provide a significant improvement in sound quality and so are equally good value for money. For me, though, the standout are the Grado Labs SR325x headphones. They are solid all-rounders with a truly balanced and attractive sound.

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