I have found that all HARBETH models love great tube amps. Overall they are at their best reproducing classical, jazz and vocal recordings. I eventually ended up with PRIMA LUNA INTEGRATED "HP". But the real magic came to pass when I switched to a double quad of KT150's. The "150's" brought out a new character in my HARBETH speakers that wasn't there with any other amplifier tested, and the most interesting fact was that the HARBETH's did not loose one ounce of that superb midrange mentioned in other reviews. Another area to look into, that I discovered, made significant improvements in the balance, tactility, presence and drive that the HARBETH / PRIMA LUNA paring produced, was going to large gauge (min. 10awg) power cables and some quality power input conditioning and well designed shielding. This improvement made as much difference in the overall reproduction of the audio spectrum, moreso that any other tweak I have every tried. Especially, soundstaging and bass slam. Have fun but for God sake don't give up on HARBETH. Eventually you will hate yourself for it. I think you would really love the 40.1's. It is a bit of an investment, however.