The best tube amps I’ve used over the 10+ years I’ve owned Harbeth’s are as follows (not in order of preference):
- McIntosh MC275 MKV (75-90 WPC) with 40.1’s
- VAC 70/70 Signature (68 WPC) with 40.1’s and SHL5’s
- Music Reference RM9 MK2 (125 wpc) with 40.1’s and 40.2 Anniversaries
Other tube amps owned/used with Harbeth, but not recommended based upon my experience:
- McIntosh MA2275 integrated with 40.1’s (too soft, totally lacking dynamics... very disappointing... awful pairing)
- VAC PHI 200 with 40.1’s (excellent bass, but lacking transparency, detail and air)
- VAC 30/30 with 40.1’s (excellent midrange at low to moderate volume, but lacked power @ only 32 WPC... but a great amp with a higher efficiency speaker).
The only solid state amp I liked was a Plinius SA-102 paired with an Aesthetix Calypso preamp, driving 40.1’s.