12V Deep Cycle battery with Pure Sinewave inverter for tube amp?

I believe DC power is going to sound better than any AC with or without a power conditioner. Basic problems have been the length of play time and the length of charging time. What are you experiencing? 

Put about 2 hours into my listening session last night. Connected battery to charge up this morning, and was still at 97%. Its a small amp, and is only pulling about 150 watts. Would not be feasible for more powerful amplifiers. 

It all starts at the wall. If you can eliminate the wall, so much the better.

If you want to run more might want to look into batteries from a used Tesla. They say the spontaneous combustion risk is low. 

Be careful handling lead acid deep cycle batteries! Hydrogen gasses and fumes emitted during charging is both an irritant and potentially explosive so ventilate the battery and area well at all times.

@imhififan should I be worried during discharge(connected to inverter while powering amp)? I will be doing all charging of the battery outside in a ventilated area.

If there is a danger with fumes releasing, would a gel type battery solve this problem?

If there is a danger with fumes releasing, would a gel type battery solve this problem?

Yes, Sealed Lead Acid type of battery is the answer! However,  Gel cell batteries must be charged correctly or they will permanently reduces capacity.

I used a 100AH Odyssey PC2150 deep cycle battery to power my modified Sony SCD-1.  They have vanishingly low impedance, which is a function both of their design and high AH capacity.  It's good to add a large amount of capacitance between the terminals-- particularly using an array of parallel capacitors.  This filters noise and improves transient response, even into low current loads.  Keep the battery cables to the inverter thick and short.   

I've also got a cheap furman power conditioner. Would connecting this along with the inverter benefit any positives, or should I just go straight into the inverter?

I am converting from DC to AC. My amplifier is a 115v AC amp, thus the conversion to AC must be done. Along with capacitors @dgarretson , any link you could send me on how this might be achieved would be greatly appreciated. I have no knowledge at all when it comes to electricity. Especially capacitors(had to Google what they were). 

Am thinking about putting a home stereo amp on a sailboat (large) with both 12V DC and 110V A/C (via an inverter running of the house batteries). 
Am wondering whether stereo equipment converts the a/c to d/c or does it use the a/c to power the amp/circuits.  

The purpose in asking is to see whether it would be possible to bypass A/c and feed d/c to the amp or preamp with a modification to bypass the a/c section?

The purpose in asking is to see whether it would be possible to bypass A/c and feed d/c to the amp or preamp with a modification to bypass the a/c section?

Yes, almost all audio electronics are power by DC!
Maybe you can consider install car stereo on your sailboat.