onboard audio suitable for recrding music?
 

In short I'll be doing small project with video and audio and will have only my father's PC. The dillema was if shall I bring for the long trip my external USB interface for the few tracks I'll record on MD and then digitize.

Last night I did a small test recording some music in my PC using my USB card and then for very first time the onboard mini jack.
Well to my surprise the result was very close - virtually identical recordings (subjective listening).
I guess one can only immagine very subtle difference in the order - original MD -> USB recorded -> onboard recorded.
I'm talking no audible noise - aproximately -70dB for both tracks in the PC monitored with the Sound Forge Rec/Play metters. Only diffrence an audiofile could notice is slightly less dinamics in the order above.

So my question now is - can I rely on the onboard Realtek ALC650? On my rig the front ports were very noisy but after grounding mod now the phone/mick jacks are crack&hiss free. No modes have been done on the rear 5.1 channel ports (where line in is also used at a time of recording).
Can I asume my father's PC would offer me similar performance (not very high but perfectly usable for the task I have). I know different motherboard makers have different issues but the audio chipmaker is same.
Worst scenario will be if his onboard audio have excesive noise and crackling sounds from bad grounding or part interference.
Any opinion or experience on that?