u wont see a diff in pres untill u spend at least 300. The GAP 73 is great as well. The pres in some of the newer usb interfaces actually are not bad. i recorded an entire mixtape with no pre, so im speaking from experience.
Good God what garbage price does not and never will = quality of preamp design. A preamp doesn't know if it cost 10 bucks or 1,000 the topology dictates how it will sound.
by your own thought process a trident s20 should sound amazing cause it cost 1,000 but the preamp it self is only about 5 bucks in parts the rest is all hype marketing and general fluff.
more and more gearlsutz ignornce is spewing the same exact garbage. We as an industry are getting just as bad as the audiophile fools.
you can measure the output of your interface I measured a focusrite scarlett 2i2 and the output of the line signal is flat from 20hz to 20khz by +/-0.3db a flat line thd was pretty low and noise floor was around -120db from 20hz up. 10hz an lower had a larger bump around -98db but thats normal for the topology.
go find a rane ms b1 they cost about $100- 120 on ebay new it's a that1512 design that is hard to beat as a general clean pre