I used Krell FPB750MCX and 450MCX with ARC ref3 and also ARC ref5. It is a wonderful combination. The ARC makes the mids very musical and still has enough details. It is also not to bright. The KCT has a little more bottom extention but the ARC preamps sound better in the mids. You can not go wring with this combination. Krell and ARC are a perfect match and a lot of audio friends use this combination.
Peter
Peter