My two my cents... I have owned dozens of speakers from planars to bookshelf to full range floorstanders. I have a pair of 20 year old Monitor Audio GR60s in my second system that I will never get rid of. If I did, someone would be buying the best used speakers I can recommend (for your listening tastes, anyway). Do I use them for jazz? No. My LFT-8bs take care of that thank you very much. But several thousands of Phish shows have been played by the stalwart MA GR60 beasts (with a 20 year rotation of separates) and they have never let me down when it comes to rock slam. Built like tanks. 4 ohm amp, 8 ohm amp? No issues. Tube or solid state? I’ve used both and they respond like loyal soldiers to either. Hard to find that model, as they were the flagships when purchased, but you may want to consider any of the Monitor Audio family of floorstanders. Full range beasts. Are they too “bright” for those with tiniitis or refined tastes? Maybe. They are for me if I want to hear horn music. But they will do your Dead shows full justice. Grab a pair of used MA gold from two or more generations ago and you won’t be disappointed.
