Burn-in revisited

This unit was bought back in December 2009 and I set up the unit with my Linn Kairn pre-amp using the 'tape loop' connection method - listening then with my Sennheiser HD650s.The quality of the sound was disappointingly poor - it was harsh, shrill and quite underwhelming .... I couldn't listen to it and failed to understand accolades for the Solo.  I thought I had wrongly connected the unit but 'loop in' via the tape output seems to have been the best option using high quality cables.  I was so disappointed with the sound that I rather neglected the unit in favour of my various iPods and less expensive headphones which have given good service and very good quality (@320 kbps).  Ridiculous to have swapped a Linn based system for this and  I know this is considered by many to be sacrilege.

Just recently I thought I'd give the Solo another go with a more recent pair of Beyerdynamic DT770 PROs...but this time I had researched and come across the issue of 'burn in' ..... but not just for the headphones but also for the higher quality headphone amps.

I have spent much time Googling and have now seen further evidence in this Forum thread that the Solo seems to require a very, very,very lengthy period of 'burn-in' and that the unit should also be left 'on' continuously.  Therefore I have been 'burning -in' both headphones and Solo continuously now since last Saturday 27 October with constant play from the DAB Tuner and 'Planet Rock'.    I have since played a few CDs on my Linn Ikemi CD player and it's possible the quality of the sound may have shifted but it still very bright, still harsh (in my opinion) and worryingly lacks bass.   I have also read in the forum, and other online info, that burn in can take well in excess of 300 hours (rather than the 72 hours given in the accompanying instructions) and that bass is the last area to improve.   In fact, I read that one chap had a 'magical experience' just after 12 days of continuous 'burn in' and couldn't beleive it was the same headphone amp!