[size=10pt]These phones are worth the retail price of $249. They have a wide sound stage which gives dimension to music. Clarity is strong enough to notice poorly encoded sound files. These don't require an additional headphone amp weighing in with an impedance of 50 Ohms. While they do sound good without one an AMP/DAC will definitely add depth to the music. On the negative I personally think the 6.3MM jack terminating at the end was highly unnecessary. Instead Sennheiser could have had an screw on jack where the 3.5MM jack can be coverted to a 6.3MM one with a simple screw on adapter as found with the Sennheiser HD 380 Pro.  [/size]

This is a decent card for the price. This card comes with good but not great components. If you want better you will have to dish out more $$ but for the $67 I spent for this I think the quality is more than adequate. This was a breadth of fresh air coming from the Creative camp which has been problematic ever since direct sound was dropped from Windows. This is not to say that the D1 had its fair share of audio issues in games like Fallout 3 but then again I had these same issues with the Creative Fatality Pro which leaves me to believe that this may be an issue with the game engine not supporting add on sound cards. Holding the D1 in your hand will give you an idea of the workmanship that went into this device. While the D1 is capable of accelerating audio in hardware I personally found the Xonar Unified driver in Low DPS Latency mode to be more responsive than the Asus driver. Low latency mode removes hardware acceleration on the Xonar AV 100 chip on this card but with most modern games off loading sound processing to the CPU, hardware acceleration is not a must. In my experience I have few issues with game audio in Low DPS Latency mode. If you have a processor released over the last five years, you would not have to worry about loosing significant frames due to offloading of sound to the CPU. Whats important to look at from a sound perspective is the DAC and Op-Amp which are responsible for the sound quality on the analog outputs. The D1 boasts a front channel Audio DAC (Cirrus Logic CS4398) with a signal to noise ratio of 120db which is nice and a JRC NJM5532 Op-Amp which is good at this price point. I am looking at upgrading from the trusty D1 to the Xonar STX to power my Sennheiser HD 380's and Senn HD 598 as the STX has a headphone amp capabable of driving cans up to 600ohms. A low budget alternative to the STX would be the Xonar DG priced at $30. Bear in mind that the DG while boasting a headphone amp will not have enough power to drive very high end cans like the Sennheiser HD 650 or 700 (The Xonar D1 does NOT have a headphone amp). Other alternatives to the Asus line up are the Omega series but while I have herd good thing I don't have any first hand experience with them. I have seen some folks talk about distortion/noise on the front panel analog out, I had this issues with the D1. However I isolated the issue to not the D1 but an uninsulated cable in my case, when I upgraded my case to an Antec 600SE the first thing I noticed was the front audio out wire was thick and well insulated, thereafter the noise/distortion was not present.             

This was recommended to me by a friend and because of the other great reviews on the web I purchased a pair. What I can say is that it really brings out the details in music. Those low bit rate MP3's will not sound too good now. Bass is not exaggerated and highs are nice and smooth. The quality of the DAC is very important for this set of cans. The distortion in the mids were largely mitigated with the use of a high quality source (Guess my Xonar U1 was not not as good as I thought). They are highly detailed with a small amount of coloration due to the closed design which can be expected. 

I honestly think you could spent your money elsewhere whether you like a flat response or want thumping bass. I can imagine if these need an headphone amp to truly show their colors but then again Bose should make this point clear on the packaging. I could not find the impedance listed nor the frequency response. Typical big brother attitude from Bose but they must have forgotten their are others now to give them a run for their money. Either way bad experience as I could not get satisfactory sound for the price. Most mid and upper frequencies sound muffled. Breaking in for over 15 hours did nothing.  

These are a wonderful pair of cans. They sound warm and natural but with some bias towards the upper end but this is not bad at all unless you are looking for absolute flat response. For general listening they are a gem. Highly recommended. They went out of production in the mid 2000's and replaced by EH350.

These are a nice pair to own if you crave for natural sound on a budget. They belong to the Sennheiser Professional lineup after all. Don't get me wrong these are not going to come close to the $1500 HD800 but for the price can't go wrong. Just wish the ear pads were a little softer and while they can still double as over the ear for people with small to medium ears, larger pads would be welcome personally. These are advertised by Sennheiser as On Ear cans. Those looking for pumping bass look elsewhere. These are the closest thing you can come to the venerable Sennheiser HD497; now out of production. Response is significantly flatter compared to the HD 497.