Quality between preamps; This question has probably ended more friendships amongst sound engineers than any other!! :)
I think what has been established is that amongst "average preamps", the difference in quality is a very subjective matter. In preamps when you talk about quality you talk about money, which the majority of us don't have.
The happy side is that you can achieve high standard recordings with the majority of average preamps found in mixers and DAW's, and its down to recording technique. Establishing optimum gain, mic choice, mic placement in relation to the talent and within the room, room treatment, training the talent with microphone technique, use and placement of pop shield, attention to voice plosives, clicks, sss, exploitation of proximity effect or not, an so on. So for us that cant afford a boutique preamp, technique is the thing to worry about. The day we can afford one we will want to cry when we hear the level of quality we have achieved!!!
The more circuitry you add to the signal path the more noise you will induce and supposedly there is a 3dB loss in signal every time you add a connector to a signal path, so I would keep it as simple as possible. . I don't think the Yamaha has direct out's.
Hope you have fun trying different set ups!