Which Harbeth Speakers

All excellent for acoustic music. The SHL5's have this wonderful big sound and are very forgiving of the equipment and less-than-perfect source materials. IMO they are much more coherent and open than the C7s. The M30's are very nice, but not as much lower mids, which can make them sound thin in the wrong room. OTOH, if you have a boomy room, they are a great choice. But you won't go wrong with any of them. Never heard the little ones.

That's probably true, but it doesn't mean you'll like them better. As I said above, the SHL5s sound bigger and are somewhat more forgiving. So many people around here are worried about "detail" and then end up whining that their systems are too forward or harsh. Keep in mind that we're talking degrees here. The SHL5s are perhaps only slightly less "precise" than the 30's and offer a bit more warmth, IMO. I've owned both, BTW. Anyway, they're all great speakers and it's your money. But they are expensive, so it's best to be honest with oneself. If you don't have the best components, or you really know you would prefer the bit of extra warmth, you know what to do. Obviously, the best way would be to try them both in your room, but that's not always possible. Best of luck.