If you asked me last week I would have said, and probably said in the past my Quicksilver Mid Monos are the best bang for the buck. Great amps, awesome value new....incredible value used like I bought mine for $1050
However I just replaced my preamp with a Zesto Leto Preamplifier.... $3500 is not cheap , but I had the opportunity to buy a NIB new old stock unit and it is incredible.... Easily the best money spent on hi fi in a long,long time. Literally sounds like I revamped my whole system, its that good. Zesto support is top notch too.