I have 40.1's and have used them with two amps. First was a Primaluna Dialogue Premium HP integrated. This amp was magical with them, but upgrade-itus got the best of me and I now run a Lyngdorf TDAI-3170 integrated with them. The Lyngdorf is the best I have heard. You should definitely look into this wonderful amp. I mainly listen to analog through it and it's just awesome. It's room correction is the difference. It also has an excellent DAC built in that is pretty great.
Also, I'm a huge Radiohead fan and have all of their recordings on vinyl. The Harbeth speakers are an excellent match for their music. Radiohead have pretty good dynamic range and excellent sonics in their recordings. Harbeth speakers are meant to present the music as it was recorded, and I will attest to this in my experience. OKNOTOK on vinyl is one of my reference recordings. I often play the MQA version of this on Tidal for comparison. Both sound wonderful.