Germ Big Muff:Battery vs AC

I received a Germanium 4 Big Muff for this past Christmas and have been using a visual sound 1spot to power it since I got it. The distortion side was excellent, but the overdrive sounded like somehow simultaneously gooey and grainy trash and I wondered why It sounded so bad compared to the one personally owned by a GC employee that he was nice enough to let me try. (yes I know GC workers are notoriously evil gremlins but that has never been the case at either one I have been to, they've only ever been helpful to me.)

A month ago, my 1spot was destroyed by my dogs and. since I haven't been able to get a new adapter, I switched to batteries since my drummer had a few packs lying around. The difference was immediate, the distortion sounded better than ever and the overdrive became that great vintage tube amp-like drive that germanium users brag about; a total night and day difference.

So my question is: is there a way to make AC adapter power sound like a battery? I love the sound but I don't want to have to buy 9 volts for one pedal or risk it running out in the middle of a set unless that's the only way. My first thought was making a voltage sagger for it but considering there was a difference with the distortion side too (which already has a volts control) it probably wouldn't make much difference.

So any suggestions? I won't mind building some external filter for the power jack if I have to.