Musical Fidelity M6si integrated amp
220 wpc, about 35 pounds and sounds wonderful on my PMC speakers. Class AB and should sound terrific with your Harbeth speakers. Its design is dual mono. I was so impressed with their sound quality, I purchased 2 of them.
See Upscale audio review of this amp link below
”Internally, the M6si is configured as 2 independent monobloc power amps with a separate pre amp. It is, in fact, a pre amp with 2 monobloc power amps that just happen to share the same casework.
The M6si has 220wpc. It has very low distortion, outstanding noise ratio and extremely flat frequency response. Its inputs are phono (MM/MC), 4 line level, 1 balanced XLR and 1 USB ‘B’ up to 24bit 96kHz asynchronous.
The M6 combination of high power, high current and extraordinary stability means that it can drive any loudspeaker with ease.”