I don't have any experience on the DB750, but it is my uneducated guess that it would work fine in the studio, given any particular path to tape you take. If you like the sound, you're probably alright. One strange thing I like to do with amps I try to find out to what extent I can boost or cut mids, trebble, and lows. If the amp is capable of going to either extreme direction away from your prefered tone, it should be able to handle anything in between. Some amps with only a few knobs can do this (I don't yet like gaphic EQ's on bass amps very much). Though, I've had some amps, that even with some knobs set in crazy possitions, it's variation from the more neutral tone is pretty minimal; this means to me that it isn't the most versatile amp out there.
i think it'll probably be ok it's not the most versitaile pre out there and it can be a bit "woolly", but if you like the tone then wth? to me the strong point of the 750 is the power section - scary loud
The DB 750 has a tube buffered Jensen transformered D.I. You can switch between pre and post eq. Before I edited this post I wrote "it sounds good'; but after I thought about it, it didn't seem appropriate for me to give a self-promoting opinion. But......fact is we were nominated for a TEC award for our DB 900 tube direct box.
I used it as a preamp in the studio for the bass tracks on a cd. Very nice even tone with a natural compression...the engineer did not need to add any additional compression (you know how they are with the compressors) to get a juicy fat tone. I acutally liked it better as a preamp than a stage amp. Not sure about the post above about tweaking knobs to their extreme for sonic versatility. I will say this amp does not go to sonic extremes, but has a wonderful warm vibe in the studio. The knobs are slight tweaks on its already charming character. If you want mucho sonic versatility, go for their losta knobs preamp only (DB659?). I did not mic a cab when I recorded with it...just ran an XLR out of the very nice direct out to the board...post eq on, deep switch engaged, bass on 1;00, everything else flat...very yummy. I sold the amp because it and my back had a fight...but may someday buy the preamp only version specifically for the studio...it was that good!