Possibly Dumb Question re:Battery as a power supply

"Sealed absorbent glass mat (AGM) batteries like OPTIMA® Batteries do not spill, sulfate or degrade like flooded batteries do. AGM design holds the electrolyte in suspension while keeping it in constant contact with the active lead material on the plates. This results in higher efficiency when both discharging and recharging.

AGM design offers lower internal resistance and greater plate area, which provides superior starting power, the ability to recharge much faster and higher voltage characteristics during discharge."

The blurb goes on to mention the Optima digital trickle charger, which I also own and which I recommended to the OP. I have used Optima batteries in all my collector cars since the early 90s with zero problems. I have also run 12V tube filaments with a huge Optima battery sitting in my living room, for several years, with no problem. Shame on you for not having one in your Porsche. After a conventional 6V battery, chosen because it was an accurate reproduction of the OEM Porsche 6V battery in my 550RS Spyder, puked acid into the forward area of the car, I replaced it with an Optima 6V battery, which you can even mount lying on its side, as I did to make it fit into the Spyder. (Early Spyders were 6V.)

Clearthinker, The question asked by the OP was not "whether" he should use a battery to run his turntable.  The question was whether he should spend $1200 on the Clearaudio battery and charger vs using some other battery. I don't disagree that maybe the OP would be best off with an outboard linear regulated 12VDC power supply, but I certainly do think the Clearaudio battery and charger are overpriced and could be replaced by excellent much less expensive equivalents.  (Actually, now I think of it, there may be a voltage regulator built into the turntable, which is why it can be run by a simple external battery.  So maybe the outboard linear supply need not be regulated.)