have you tried midi? your assumption that it will not sound good is not corrrect. the quality of sound does depend on the synth and the sample but lots of us use midi and in fact - i believe - playable RealTracks are midi using the samples from the RT recording. and of course finding the audio you need of the right three notes is almost impossible. with midi you can choose exactly what you want. for a full discussion on this read the post here............
https://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=777473&page=1read the post and if you if you follow the link i put in one of my posts you'll find a sound clip of me doing exaclty what you want to do with a specific set of notes and midi