quicksilver v4 monoblocks

They are powerful, great, great bass, and magical midrange, which is the trademark of QS amps. I have never heard anyone say anything bad about QS, look and search. I compared them with my CAT JL2 which are among the very best P/P tubes amps in the world, and while ultimate I prefered the QS, your talking about amps 3x the price and I could have lived happily with either. These amps are neutral with tube bloom, but not classic euphonic sounding - that works for me. You'll not find a more reliable, lifetime amp on the market and you will always be able to sell them for what you pay for them if you buy used - quickly to. I don't know what elese you are considering, but I've been a QS fan since my first 8417s years ago, and they remain Amercican made, reliable, with sound engineering and no flavor of the month nonsense.

also considering the atma-sphere m-60 mk3.

Another excellent choice. Are you speakers appropriate for OTL? I think you could love both.

Second the recommendation on the QS. If you can find an MX-190/MS-190, a MS135 or the 120's, get them. The older MFA tube amps are great also!

I agree on the older QS, and somewhat more tubey then the V4s. I no longer own QS, but I'm a big fan of both the product and the straightforward approach to design and promotion taken by Mike Sanders. That being said, Ralph Karsten's amps are well worth considering, if your speakers are OTL friendly.