These headphones have a real retro style and feel that wouldn't look out of place in a world war two German U-Boat. Build quality is good but not superb (Sennheiser probably has the edge here). Some complain that the thick cable can detach from the headphone casing and require resoldering - so handle carefully. Plus the cable is far too short for most general use at 6 foot - my 1970s Sennheiser HD424's lead come in at a far more useful 8.5 feet. So expect to huddle in close to your amplifier. Plus the lead only has a 1/4" [6.3mm] standard jack, with no 3.5mm mini-jack for MP3 players/TVs. The headphone lead is also very thick and inflexible, so it's relative shortness isn't that helpful when using a small MP3 player [with the optional Grado 6.3mm to 3.5mm converter] - again my old Sennheiser leads are far far thinner so their extra length actually takes up a lot less room and their cable/plug pulls less on the mini socket. For my MP3 player I use a lighweight pair of £60 noise cancelling Sennheiser PXC 250 headphones [that are great and come in black or white varieties], so the Grado 125s are used strictly for the home HiFi. However these thick Grado leads probably mean thick wires, suggesting better sound quality. And that's where the headphones do excel. Bass is powerful, treble sweet, mid-range clear, with a typical open-back spacious soundstage. I listen mostly to rock, pop, folk and a little classical music. These headphones sound best with high quality sound sources, i.e. they can resolve the music detail and dynamics. With a duff MP3 player, that's say bass light and bright, they will show up the inferior sound source ruthlessly [so don't blame the headphones]. The light weight and soft bubbly foam ear cushions make for comfortable long-term wearing, although I had to very slightly bend open the headphones on first use to stop them clamping far too hard on my head [after which they were OK]. Some complain they are uncomfortable for extended use, but once modified I have found them fine. Alternatively you can slowly 'wear them in'. These are supra-aural headphones, i.e. the foam cup presses firmly against the ear rather than surrounding it. The headphone cups swivel round, so you can put one cup against the ear recording engineer style, if you don't mind forgoing sound quality and stereo image (actually handy when recording and checking levels etc when the TVs on).
I did have to spend another £40 on the Grado 450cm [15 feet] extension lead [6.3mm jacks] and the Grado 15cm mini-jack adapter [6.3mm to 3.5mm] lead to give the SR125's full functionality. These very solidly built Grado extension leads work really well (unlike the £12 generic one I had that never connected properly). Plus the extension cables 'are constructed from the same high quality wire as Grado's headphone cable'. I knew that the headphone lead was too short, there was no 3.5mm adapter, and that I would have to get these extension cables after I bought the SR125s though. With the massive Grado extension lead I can now sit anywhere in the room and sound quality isn't compromised. So other than the few gripes [which lose the SR125s a star], I can recommend these Grado SR125 headphones for serious audiophiles.
I have used these headphones for four years now and like them a lot - my HiFi is quite expensive & largely British built, and these headphones compliment it well for CD, tape, LP and TV sources. More importantly I don't get any bass distortion when playing loud(ish), which led to me dumping my old 'Cyberman' Jecklin Floats. Overall, I like the retro look, like the punchy `rock and roll' sound quality, but always handle the headphones very carefully [and never let the kids use them]. I haven't compared these SR125s to their identical looking but cheaper Grado SR60/80's siblings though, I just took Grado's word for it that they offer superior sound quality for the extra money - independent reviews seem to confirm this. The SR125s feature 'an improved diaphragm and voice coil design and UHPLC [Ultra-high purity, long crystal] copper voice coil wire' compared to the £80 SR80s. I chose these over Sennheiser models, but have yet to discover what Grado's after sales support is like. With my 1970's HD424's I can still order spare foam pads for them cheaply from Sennheiser, and when they were many many years old I could still even buy replacement HD424 leads and speaker units - which is fantastic after sales support. I just hope Grado can match this when I need it.