Battery Powered Amplifiers?

I am looking for a high-quality battery powered amplifier. I have seen a few listed on eBay and one from DIY Kits but I figured I would ask the crew here to see if such a beast exists. The power to my condo is noisy and fluctuates between 100 volts to 122 volts. The frequency is solid, relative to the voltage.

I would rather invest in a battery system than big $$ on line cleaners and isolation. I have a medical grade trip-lite line isolation box and step-up/step down transformer that was used for NMR machines at the U of I lab. It does OK, but I think DC to DC is the way to go for purity of sound without huge $$ on electronics.

Any thoughts? Under $1k for vocals, singer/songwriters, blues and loads of jazz. This will be used with Totam Hawk speakers, McCormack Line Drive passive preamp, Linn Sondek LP12 and Ray Samuels Nighthawk battery phono preamp I am about to order.

Thank you in advance - D