The H2O S250 Dual Mono is a superb ICE Power amplifier designed and hand-built by Henry Ho of H2O Audio (NOT the waterproof headphone company in California). Utilizing a huge, analog power supply, It produces 250 watts per channel at 8 ohms, 500 watts at 4 ohms, and is stable at even lower impedances.
I purchased this amp because it is one of the very few that can easily drive my Apogee Scintillas, which are 1 ohm speakers that can drop below that. Henry designed it specifically for his Scintillas and for other low impedance loads. It has not been used very much, as I never found time to use my Apogee system on a regular basis, and am now starting to downsize everything for an eventual move to a much smaller house.
There are two sets of speaker terminals per channel for easy bi-wiring, and there are both balanced and unbalanced inputs.
The bass from this amp is exceptional. There are reviews (for both the two channel/dual mono and mono versions) from a few years back on iceh2oaudio.com, or you can easily find them by searching.
This is in near-new condition. I rated it as a 9 to be safe.