The First Watt amps ARE very speaker specific, and Pass or Reno Hifi one of their main distributors will be the first to tell you that. If you've low power requirements, i.e., Abby's, or a pair of monitors then sure one can hardly do better than a First Watt amp.
Observing more first generation First Watt first amps on the used market of late I assumed was attributed to the fact that Pass made a major design change with the use of mosfets. I was considering buying a used F1 a month back. An email to Pass requesting the cost for the upgrade received a reply stating Pass isn't even allowing upgrades to those first generation amps until all first generation buyers have had the opportunity to upgrade their amps. In other words, I as a second owner couldn't upgrade the amp. I first thought that's fair, until I observed upgraded first generation First Watt amps available en mass from distributor Reno Hifi. So obviously dealers get the head of the line too. Sonically speaking First Watt matches well with single source driver speakers. But they'll not drive 65% of speakers on the market, hence the reason for distributor's offering a 'buy and try' sales strategy.
