If you want to know when a Cloudlifter would be good, have a look at Matt's
http://recordinghacks.com/2012/06/18/sm7b-audio-interface-shootout/If you want to roll your own, read ALL of
http://www.groupdiy.com/index.php?topic=5743.240Loadsa stuff from true gurus and pseudo gurus like me too. And sources for Unobtainium bits etc.
One suggestion I make is that if you have a
low output ribbon with a nominal 200-300R output, you'd be better off making a
dedicated preamp using THAT1510 or another of the excellent single chip solutions from TI or AD without P48V.
But making up a complete preamp so it approaches the
1nV/rtHz performance of THAT1510 is a major undertaking. In particular, the PCB, wiring and construction has major implications in Low Noise design.
A simpler solution, much more likely to result in success is to take a good existing preamp, remove P48V & other evil bits and
optimise it for 300R ribbons.
An obvious candidate is the Seventh Circle box with their T15 modules.
http://www.seventhcircleaudio.com/T15/t15_about.htmThis is a deluxe kit using only the very best components. It costs $99 for a single channel module … and you need a box, power supply etc on top of that. But if I was rich, had the space and wanted to build a state of the art preamp, I would probably start with one of these.
But you can get a discontinued
M-Audio DMP3 for less than US$100 on eBay. It has a good reputation in some circles but is rather noisy.
If there are sufficient people interested, I'll start a thread on how to convert a DMP3 into a dedicated ribbon preamp with much lower noise along the lines of
special order Millenia Media preamps and the
AEA TRPAs a pseudo guru, I won't be doing any of the dirty work myself but counting on yus serfs to butcher their DMP3s.