It stinks the tweeters let go but better the tweeters than the crossovers or amp outputs. As Ben stated had your RR2150 output full rail voltage the level of carnage could have been much greater.

I am not sure what might be involved in adjusting the volume control to never allow the amp to output past rated output. Ben should be able to tell us what might be involved.

Being used to the volume control in your Luxman I understand how this could happen. I did the same thing way back when taking out a tweeter as well as the crossover in one speaker. I feel your pain.

I agree with you when it comes to pro amps in the home. Cheap power for subwoofers but not much else. If I were shopping for a used two channel amp I would hunt for an Adcom GFA-555. Nelson Pass designed class AB high current with no issue driving 4ohm loads. Parasound is also a well regarded brand.