The HPB-1 sounds fantastic and is super quiet behind a active bass. I took a chance because I have been disappointed by so many items on the market that at a hum to an active bass and sound dead so I spent the money and found this one used for about 500 bucks. Awesome, awesome, awesome preamp. Not much tone wise that you can't pull out of it once you get used to the fairly simple controls. I have played a ton of equipment with tube preamps, this is the first tube preamp that sounds like a tube preamp, but it still retains the solid state detail. So incredibly happy with this purchase.