I had a chance to compare Krell 400xi with Krell 750 MCX monoblock, connected to a pair of Revel Studio/Salon(not sure with the model, it was the most expensive model of Revel loudspeakers) with Nordost Vahalla (not sure with the spelling). The expensive monoblock produces beautiful sounds. After I listen to the monoblock, I asked the owner to change the amplifier to the Krell 400xi that I was going to buy. The difference is very subtle, only in the very minute passage of the song that I can pick up the difference. Considering, the amount of money that I am going to spend, I think I should be very happy with Krell 400 xi. Hope this helps.