I'm using Cubase Pro 10.5. I have had a Virus Ti2 for a while with no issues as it has audio over USB. However, a couple of recent synth purchases are hardware with USB over MIDI but no audio over USB. That means I need to create these as instruments to use within Cubase.

Any ideas on best and most efficient way to do this so I can add them to projects with as much ease as possible?

Cheers!

 

External Device (f4) or midi + Audio Track

 

You'll need a multi-in out Soundcard, but @Tannoy is bang on.

 

If you have a multi in audio card, just connect the audio out of your synths to the inputs of your audio card, then in cubase add a track MIDI, select the new midi track, in the left part of the arrange (inspector) just select as MIDI IN the midi input of the master keyboard that you will use to play, if you still have the Virus TI just use Virus TI input (is the USB midi in). If you have a classic old synth (no usb midi) u need also the MIDI port hardware to connect your MIDI in out cables 5 pin din connector.
To listen the input audio just click on the rec button of the track or click in the yellow listen button, the audio monitoring is affected by the latency of the audio card so you will hear it delayed.
Now u can directly record an audio track by keep monitored the midi track with yellow button, adding a new audio track and select the INPUTS of your audio card where u plug in the output of your synths, or like the 95% of the composers, record first a midi track, editing then recording the audio track as said before.