Hello
I completed my Crack a few days ago and just added the Speedball upgrade. Everything went together and passed all tests without a hitch and I've been enjoying the amp with my HD 650's and BorderPatrol DAC SE. Overall I prefer the sonics with the speedball installed but to my ears the highs are slightly too aggressive. I'm interested in finding a tube compliment that will yield a more relaxed presentation without sacrificing too much detail. Also I've found that the supplied 6080 is somewhat microphonic and periodically develops noise in the form of a soft, high pitched whine in the 1~6khz range, usually in the left channel. It's very faint and it comes and goes, but I'd like to find an output tube that's quieter. Do the 6AS7G's fare better?
Thanks!