20 Watt Battery-Powered Amp Concept

[SurreyNick]

I thought it might be fun to try and build a c.20 Watt battery-powered guitar amp from bits and pieces I have lying around and would invite thoughts and ideas on the proposal.

My initial idea is to use a TDA2005 in bridged mode for the amp, which the spec claims will typically produce 20 watts at 14.4 volts on a 4 ohm load, and precede this with a pre-amp stage based on the MXR Distortion Plus using a RC4558, the circuit driving a single Jensen Chicago 8/20 MOD Speaker (8 inch, 20 watt, 4 ohm) with the whole thing powered by a Ritar RT1250 12v 5.0Ah SLA battery.

The amp would only have volume and gain controls and the battery would probably be exhausted within two to three hours at full volume, but these are components I have lying around so I won't have to go shopping for anything.  However I'm open to ideas, especially those where the build is quite straightforward.

What do you reckon?