Yes, I understand the rigors of studio work, and also the innate and very personal preferences of studio engineers. The 45 year old pair of passive studio monitors came to me from a rather accomplished studio engineer, who said he had heard that I might be able to help him get his favorite monitors working again for his studio. He said up front that cost wasn't an issue, but that they needed to sound like they did before the failure. Well, I first re-capped both of the crossover boards, and also measured the other passive components hoping to find a failure. This I had said up front was needed work based on 45 years of age, and optimistically "might" solve the issue IF it wasn't a bad driver. That work led to the conclusion that one woofer had a failed voice coil. I removed the voice coil from the woofer and inspected it as well as carefully measured it - diameter, former type/length, length of winding, layers of winding (thickness to fit the magnetic gap), gauge of wire, impedance. Repairing it and/or rewinding it were not a likely solution as the break was invisible under magnification. However, I located a suitable replacement with the same parameters from one of my suppliers and ordered two. I installed one on the failed monitor's woofer and then measured both monitors, very carefully. They were a close match within tolerance so installing the second voice coil on the "good" monitor's woofer, nor completely replacing both woofers in their entirety was not necessary (and avoided a larger risk of affecting the sound the engineer was used to). Customer was happy as he had back his favorite monitors fully operational, working as original, with original drivers, and re-capped crossovers for a reasonable price. He put them to use immediately and then paid my invoice with profuse thanks. I provided a 10 year warranty on the repair, but fully expect them to last another 45 years - when we'll both probably be gone.
Had they been active monitors I would have had to perform circuit board level troubleshooting, and if that proved unsuccessful converted them both to passive.
Now, the topic at hand here is these small $4K 8351B monitors, which replaced the 8351A that preceded it, so that clock to get spare boards must be already ticking for the purchasers of the 8351A monitors. If I were the one buying then I would most likely buy one spare complete monitor in addition to the pair to make absolutely sure I had access to space parts. The fellow that posted the picture of his home theatre system had 5 of these speakers, a $20K capital expenditure. Had it been me I would have added 2 spares making it a $28K capital expenditure. That's pretty pricey IMO for a home theatre system that doesn't generate revenue, but if it brings happiness I guess it's good. IMO it would also sound better and bring more happiness without the reflective "coffee tables" in front of the listening position (zero cost).