Sorry for a late response, just saw Your questions now. The main differences is that stock Glock preamp is two band, and Darkglass Tone Capsule is three band EQ. Also, stock EQ is Bass and Treble, and Darkglass is Bass, Lo Mids and Hi Mids (70 Hz, 500 Hz, 2.8kHz) - I think only one 3EQ at the market without classic Treble frequency.... I Love it! I had a stock Glock preamp in my TM4, but with Darkglass Vintage Ultra V2 pedal I was more happier with the sound then using on board Glock. Then I found that Darkglass makes Tone Capsule preamp with almost the same EQ frequencies like on a Vintage Ultra pedal. About that time Sandberg introduce Grand Dark model with Darkglass Tone Capsule stock on board, so I decided to change mine for a Tone Capsule and have the sound I like from the Vintage Ultra V2 pedal preamp. Since mine stock Glock was two band EQ, I contacted nice people from Sandberg, and they sent me the wiring scheme for three band EQ and stacked potentiometer with double knobs for third EQ. Tone Capsule I ordered through Thomann Germany Sandberg dealer, and everything arrived together with the stacked pot, knobs and wiring scheme. There was no need to mod anything at the bass itself. Just a little fine soldering. Nothing special if You are familiar with the wiring schemes. Hope it helps Here are two pics from outside, one with stock pots and the other one with Darkglass 3EQ.