Agree with your guys, the line out is good, and the HP out is good for high impedance too, but crappy in driving low impedance earphones. THD is very high with low impedance earphones, especially on the high frequency, appears to be brighter but are actually high frequency harmonics...

Actually I am tempted to make a cover out of maghony.

use your hand grease and you can refinish the back with layers of sandpaper and grinding wheel.   I've done that, and pretty much the case they sell on ebay is refurbished this way. Or if you have a sandblaster, you can also make a matt finished back case easily.   And finally, only if you...

Get the U2 back and there will be no hard drive size etching on it. Of course, only if you don't mind the "U2" signature.

If you have the thin hard drive, Toshiaba MK1634gal, it will definitely fit in the thin profile. Just be warned that opening up the iPod classic maybe a challenge, it is very likely you will bend the back case, a perfect excuse to replace it with a thick backplate and 2000mAh battery.

Not possible at this moment, unless you can do some serious soldering to have I2s audio out.    From the datasheet the process can handle toslink output, but the hardware is not implemented.

There will be no limitation on the hard drive size (<1TB).    I've done test with 160gb hdd on 120gb mainboard, not a problem. 

  I totally agree on you reason for buying Tarkan, just like buying a car, our purchase is rarely based on the technical specs, but a bloated horse power or MPG number will definitely make people mad. 

Right, continuous playback.

I just want to reiterate here that  the above comments is not backed by any data, and more and more of you will find out from your own experience that it is not true.

I stand behind my test result; ipod 5.5G, 64mb RAM, 2000mAh battery, crucial 480g, generic green adapter, a mix of regular mp3, various coding rate.  And my battery is tested with my DIY microcontroller capacity meter so it is true 2000mAh. It took me a few weeks to make the capacity meter...

RB battery capacity setting will not affect battery charging terminate voltage. The 1400mAh /2000mAh number is used as a reference for battery life prediction.

1 is the way to go.

So DC bias for this AMP is not a problem, DC servo can work quite well, so do you have any pop at start up? From what I am reading the OpAmp on the UHA6S MK2 can be easily swapped, and I am sure you will enjoy that.

Wolfson output have a 2V DC bias however for capless setup, both the positive and negative have the same DC bias level, the TPA6120 will take that as a differential input, and the net output from the TPA6120 AMP is zero DC bias. You may check readings online related  to "xlr balanced audio" or...