12 Volt LION 6.8 Ah the Tascam drinks between 340 mA and 400mA with all Phantom On relative cool running device= good sound 4.8 Watt SONY is King PCM D50 0.5 Watt. Dont make the wires Battery/Device to long 8 inch is much to long. An if you can put some Bypass Low ESR parallel to the external Supply.
Dont use the bare LIPO or better LIPOFE4. Put several 470uF/16V Rubicon black Gate Low ESR in parallel. Recomended 20 Pieces or more 470uF/16V and cut of the plastic housing from the caps. Sound depends on the capacity of the batteries size deeper internal impedance = more control, less influence the wires and the connectors, LiFePO A123 are best and safest. LION is not as good has some protection circiuts wich gives a higher internal impedance.
The secret of good sound with LiFePO4 is give easy and fast a big amount of current many amperes...
http://www.computeraudiophile.com/content/Just-upgraded-Hiface-EVO?page=3#comment-59989Headroom knows his stuff. Listen to him.
Any battery technology must be appended with low ESR capacitors so that the transient currents dont sag the voltage. This is what sucks the life out of your music. Also, the wiring that you run from the battery pack or the capacitor bank to the circuit is critical. Not just loose wires, and the gauge and geometry matters.
His charging guidelines are also good, although this must be evaluated for every circuit. Regulators need some headroom. If you get too close to this headroom, they will fail to regulate well, resulting in varying voltage and poor sound quality.
Steve N.
Empirical Audio