My point is they are old and need to be recapped to be reliable... BTW my RS4b's with their stupid crossover design that has two dips to 1.7 ohms at 2Khz and 1.6 ohms at 50HZ made an Adcom 555 release the magic smoke and it was only two years old at the time.
I had a 555 die a terrible death using it to drive Infinity Quantum 5s with the Watkins woofers. I just sold another GFA555 because I just don't trust them. That goes for any Hafler amps also. Had one of those catch on fire momentarily driving the same set of Quantum 5s before I yanked it and set it out on lawn to cool down. It was a mess and went immediately to the dumpster