My reference for reviewing the HD 650 is the AKG K701. I've used the HD650 with various amps and sources including the Nuforce HDP, Headroom Ultra Micro Amp (now discontinued), the Beta 22 (2 channels), Musical Fidelity M1 and the ALO Rex MKII. Sources included Marantz CD5003, Ultra Micro DAC (discontinued), Ultra Desktop DAC (discontinued) Nuforce HDP and Centrance DACPort LX.   I think many reviewers have already talked a great deal about the characteristics of the HD650. Most of them have better experience and probably are more capable of...

Both K501 and Sennheiser's HD600 are the sweet points of Head Fi. They are sold at a fair price and they do nothing wrong, they only differ in the way they reproduce music. While the HD600 is soft, smooth and mellow, the K501 has more detail, transparency and more extending treble which is never harsh or piercing in comparison to the K701. The mids of the K501 are magical in comparison to the K701 which is a bit recessed. There is a sense of immediacy with the K501 which brings you closer to the music, a feeling I never had with the K701. It's a pity...

I bought the AKG K340 Electrostat-Dynamic System twice. The first pair was very worn out and sounded weird so I sold them after a while. I bought the second pair from Ebay, and this one sounded very different. I used the first pair with the Beta 22 amp which really struggled to drive it properly. The second pair I'm using with Headroom Ultra Micro Amp with Astrodyne PSU, and surprisingly it drives this pair with no problem, I hardly pass 10 o'clock of volume!   I suspect that the second pair is the bass heavy version. There is a lot of bass here...

I owned the Nuforce HDP for two months, I tried it with several headphones ranging from the 600 Ohms DT880 to the 300 Ohms Senn HD600 and HD650 and 62 Ohms AKG K702. Actually I wasn't impressed that much. I didn't feel that the amp had enough juice to drive any of the headphones mentioned above, and the DAC had too much emphasis on treble which seemed too exaggerated and unnatural to my ears. When listening to several audio tracks and in comparison to Headroom's Ultra Micro DAC I heard distortions in the upper highs that never showed in the Ultra...

The HD600 is one of the best headphones around. They are neutral, easy to drive, comfy, with a touch of warmth and enticing natural presentation and timbre. I didn't like them the first time I bought them with the stock cable. I bought another pair driven by the formidable Beta 22 amplifier and the HD600 was transformed into another league.    Although I listen mostly to my K702 which is more accurate in comparison to HD600 warmer tone (which is closer to concert hall sound IMO) I save the HD600 for very special listening sessions, I don't use...

This amplifier didn't drive my ER 4S earphones properly neither my AT M40fs! May be it's a synergy issue, but I'm not sure, at least nobody complained of ER 4S being hard to drive! The sound was too dark for my taste, with a collapsing soundstage (compared to my Onkyo receiver) and very poor extension in the highs and lows but the mids were good. I used it with my Marantz CD5004 connected by Blue Jeans RCA cables and this combination was awful! I guess the dark Marantz is not the best combo with the dark caliente. In the end I think there are many...

The K701 is not the most perfect headphone, but at this price range it can surely compete with headphones double the price. They certainly need a powerful amplifier to drive them properly. I never appreciated them truly till I used them with the Beta 22 amp and then I found out what I was missing on the lesser amps I used. The best K701 I heard where used around 1000 hours. They sounded very smooth, relaxed and a joy to listen to. They can pick up any weakness in your rig: Source, Cables, Amps. They need careful matching to sound correct. Compared to...

I'm surprised that no review has been written about those gems! The ER 4P/S is one of the best IEMs in the market value wise. They are made to last, they isolate like no other IEM and they have a unique flat frequency response which can be easily adjusted if you have a good equalizer or an integrated amp. The ER S will sound best when used with a powerful amp, it will provide an amazing sound stage and wonderful imaging of instruments and players. They can provide life like details of the recording including movements, coughs, breathing and pages...

I'll keep my comment brief and short. The sparrow is definitely not the same as your ipod or PC sound card. It's an improvement over both. I bought the A version and I use it with my Shure SHR 840 with good results. The sound is rich and full with decent imaging. For the price I paid no complaint. Audio GD were extremely patient answering the questions I showered upon them, I recommend this combo for sub $150 set up, but I believe that the uDAC is the best deal to have in this range.