LazerBeakShiek - you mentioned this +4 thing before. where are you getting this reading from? On every bit of interface kit I have, the highest the gain control can push levels to is 0dB. I have no facility whatsoever to get higher. Do you have some kind of additional meter? Even so, I can't see the point as the maximum digital level is 0, so if you plug a +4dB device in, you back the gain off to make the higher input level read correctly, and if you plug in a -10dB device you bang the gain up? The keyboard might be between the two, so again, +4dB doesn't come into it. I thought I understood your use of the term but now I've lost it. Very few people have equipment that outputs at the +4dB level on a jack or RCA it usually will be on a balanced connector. I've got mixers that output +4dB level on XLRs, -10dB level on jacks. Guitars will be lower than that, keyboards and synths hovering around the -10dB, and of course we're down to microvolts with mics on quiet sources. We're actually talking about voltages here not dB at all. so it's .775V for the unbalanced level and 1.4V for the so called pro level devices.
TRS is exactly the same 'quality' as unbalanced, it just lacks the noise rejection properties.
Roland Fantoms have this in the manual
Note: if you wish to route the sound (audio) of the Fantom-X into a computer, you will need to use an Audio Interface.
The Fantom can receive USB audio (perhaps from a mic), but can't send it to a DAW - the host computer detects it as a MIDI device and for storage, but it does not receive audio from the keyboard? It's a clever beast, but not that clever. I don't have one, but the manual and the Roland site are quite clear.
It wouldn't be that useful with a typical DAW because while Macs might be able to communicate with two audio devices at the same time, my PCs can't. So like practically everyone, Roland users have to stuff the audio from their synths into their interface. That's why I have duplicated most of my synths with VSTis - they're more practical to use.