Much as I want to support vendors like GR Research (I do not see Rythmik listed) who help sponsor AudioCircle I believe you are better served with support from Genesis. Orphaned products are a constant issue in the High-End. When a company survives and goes the extra mile to support older models rather than declare after X years no support it is worth rewarding them with your business, IMHO.http://www.genesisloudspeakers.com/upgrades.html
Quoting from the above link:
Plate Amplifier Upgrades
The G500, G501 and APM-1 were among the most popular models from the old company. Unfortunately, as these speakers approach 15 years in age, their “hearts” are no longer pumping the bass. Some of the parts of the ancient Class D amplifiers used in the plate amplifier are no longer available making repair impossible if not extremely difficult.
Hence, we adapted the plate amplifier of the current model G5.3 for these older speakers. They are not just a repair, but a full upgrade to the bass system. As a happy customer noted, “Spending the money for the new amps was a hard pill to swallow when I thought I was just going to get my old speakers back but that's not what happened. I got a new and much better pair of speakers from the upgrade and that was not expected.”http://www.genesisloudspeakers.com/g5p3.html