These compare in sound quality to Audio Research VTM-200 monoblocks, but richer and to me,equal to the Reference 300 MKII I had but less bass power, so they represent a better value and lower maintenance since a tube arc only blows a fuse rather than damaging resistors and traces as on AR. When I bought these I was told this is a unique pair made for the owner of MFA as the best Bruce Moore and Scott Frankland could make. I have owned and enjoyed the M-200 B, D and E (with full Scott Frankland updates) and these go beyond them.. Triode or Ultralinear choice by flipping two switches. Adjustable feedback to match your choice of 2,4 or 8 ohm speakers. Dual output transformers and oversized power supplies and all the best parts.. Recently new power supply capacitors and output tubes. Will double box for safety.