Hey Paul,
Actually, I’ll have adjusted the MIDI channel volumes up from zero by then. Perhaps that’s what I’m doing that I shouldn’t be. Otherwise, these are the Audio or rather the Instrument [Audio] outputs from the Vst’s, for example Kontakt’s outputs [assumed most likely to be the culprits] - but no actual Audio tracks in the songs yet.
I always start with my MIDI tracks first, then add my Audio tracks later.
For me, it doesn’t interfere that much. I just keep pluggin’ away, since it comes & goes so quickly - and so sporadically.
I only have the one Windows 7 - all 64 bit PC that I built just as my dedicated DAW rig.
I put 16 Gigs of RAM into that puppy, as well as 3 SSD’s, one 1 TB hard drive & two 1 TB external drives.
And she just hums along & purrs like a kitten! 
I’ve even been able to unplug 2 of it’s 4 fans. Nice & cool & quiet - even with all 4 fans.
The last rig was just a dual core with only 4 Gigs RAM - 32 bit. It’s now a separate house internet/office rig.
Actually, for myself, I’m already using what I think to be a super duper interface. It’s a tc electronic SK 48. I’ve had it for about 5 years now and I love it.
http://www.tcelectronic.com/studio-konnekt-48/
I’ve had no issues with it when I ran Sonar X2a & Studio One Pro 2 on it, so I think that part of the equation’s ok. I don’t think my problem is with any physical equipment at all. I’m really quite good at getting that stuff hooked up, configured and working correctly.
For yourself, I think you couldn’t go wrong withe UR22 or the UR44. I think they would integrate perfectly with Cubase, as designed.
I think that upping the RAM is always a good idea and the cheapest & easiest one that always gets suggested first. Whenever I read on optimizing the computer for DAW work, I can’t help but notice over & over again that the first suggestion always seems to be to start with cramming as much RAM as possible into the Motherboard.
My only regret, is that when choosing a Motherboard when I built this rig, I went with one that could only hold a max amount of 16 Gigs of RAM that I have in it now. It would be nice to have the room for more, if ever needed, although I really do have all the VSTs instruments, FX & libraries that I’ll ever want or need by now.
8 Gigs might be enough for Windows 8 Paul, but 4 Gigs might not be enough for Windows 7.