Great tube preamp for your 500 chassis. Works perfectly! This is a true high-voltage preamp that converts the lower-voltage 500 series supplies to the high voltage that vacuum tubes need; it's not a plate-starved design. (ie, classic tube design)

Works great, have used it on a handful of recordings in my smoke-free home studio over the last decade. Just find that I'm using my interface's internal pres more, out of convenience, so I'm letting my whole 500 rack go. See other listings if you're interested in the chassis or other pres.