Replace tubes in Black Ice 3502p

I have the predecessor Jolida 502P.  I noticed sighnificantly more headroom and a warmer tonality with the KT 150 at 600 mv per Jolida's advice.  I was surprised at the greater headroom since the circuit is not designed for KT 150 so it shouldn't  really produce any more power.  BTW speakers are Magneplanar 1.7's

I also had a 502p and you could stick nearly any power tube in that thing...I biased my KT 150s at 500mv and they sounded great, as did 6550s, KT120s, and KT88s. Certainly Jolida/Black Ice are still one serious bargain of a well designed tube amp.

kt150 will provide more power more linearity more headroom

make sure your specific amp is able to handle the big bolder badder tubes... some can't, and the results then aren't pretty...