Which speakers for McIntosh tube amp MA2275-Why?

I would like to get advices on how to select the best speakers for my McIntosh MA2275 tube amp at 75 Watt per channel. Using these opinions I will limit my search to a handful of speakers. It would be best to listen to as many as possible but there is no high-fi in my area and even listening to a hand full of speakers would require significant traveling.I live in a remote area. My budget? I would buy used,$6000 maybe? Size is not an issue and would like efficient speakers.I need fair bass response for pipe organ. Transparent with low distorsion and a huge sound stage would be nice. I listen to 30% classical 30% rock 30% Jazz 10% other. Being a physicist technical discussions may help in my preselection.

Thank you,