At least about 180 -- 200 hours (+16 -- 20 hours for amp) combined burn-in, listening and playing behind with soft-2 and Earth. Could have lot more of course, but I decided to do burn-in mostly during day only. I don't know if the other settings would be better for my headphones and mind, but at first I want to do burn-in with Earth and soft-2 and not play with the jumpers and HDAM's at this point.
Not sure if it's that my wooden ears can actually hear any difference or it's just my mind, but somehow the sound is less tiring than it was at the start. During less than 50 -- 100 hours of combined use I couldn't always listen to for long sessions, as there was something in the sound that made listening bit tiring. Now that feeling is basically gone and I think I can also hear bit more nuances, mostly on lossless songs, that weren't there at first time when I used Compass. It feels like sound is slightly more... accurate and natural now. Especially low-end bass and highs sounds clearer, IMO.
Also discovered the difference within ASIO4ALL and Directsound can be very noticeable: I played Planescape: Torment during last week and later listened to it's soundtrack again. I was almost blown away again - a lot wider soundstage and details where just incredible. It didn't feel same at all and I wondered if the soundtrack in the game has been actually resampled and processed totally downwards.
I'm also very happy that even my headphones, only moderate Sennheiser HD 595, got a such huge boost in sound quality, way bigger than I'd have expected from it's reviews and comments from forums. I've tried and used 595 with Compass amp only to test if the improvement would have come from only DAC or both DAC and Amp, and so compared the sound to the output of PC, TV and PSP - and the increase in detail, soundstage and boost in low-end and highs is still easily noticeable when only amp is used. I guess that I will use these headphones for a bit longer time than I originally thought... and that I have to finally accept the fact that even somewhat cheaper headphones may benefit a lot from dedicated amp and external DAC. Seems to be overally very good gear for a student and for those whose budget is limited.
Well, no device is perfect, so few small "cons" to mention:
- Every time you open it, the smell conquers the small room easily.
- Gain limits the usable volume range for efficient and low impedance headphones fiercely. The largest volume level for constant listening for me is just slightly above the point when the channel imbalance and such fades totally, about 7:00 - 7:30. However, it seems that now slightly bigger levels can be used due to burn-in...
- It gets hot. Don't have a thermometer nearby, but I guess it's around 40 - 60 degree Celsius. Together with PC it heats the small room very nicely.
