I have used both usb and the old style midi plugs with a audio separate interface. If you have old gear with the old plugs then I guess there's no other choice but to get a usb to midi adapter. Just to be doubly clear, you don't need that if you have a keyboard or drum machine with a usb midi output. If you have more than one thing to hook up it can be a good idea to get a midi interface with more inputs. Otherwise you'll need to change the plugs for every time you want to use a different sound module,

You all have been very helpful; thanks a lot!  Yeah, I have a couple of older Kurzweil and Roland synths that I've always used as controllers, and they only have MIDI ports, no USB.  I'll just see if GC has a MIDI-USB adapter or a cheap 1x1 interface (sounds to me like those are basically the same thing).  And I learned a lot from these posts about ASIO vs. WDM.  I think what I'll do is try them both and see (hear) if there's any noticeable difference.  I appreciate all your help.