Guitar and piano share much of the same music spectrum which makes it difficult for any 4 track stem splitter application to achieve great results.

Shlind mentioned SongMaster Pro has a 6 track stem splitter. A 6 stem splitter likely uses a different stem splitting way of extracting stems than a 4 track stem splitter. The different method may achieve better results than any 4 track stem splitter; I don't know as I don't have SongMaster Pro. If Shlind has SongMaster Pro perhaps he can run a piano and guitar test song through the Band-in-a-Box 4 track and SongMaster Pro 6 track stem splitters and obtain a side-by-side comparison.

I have a Bandlab account and have used the Bandlab stem splitter. To me the Band-in-a-Box stem splitter achieves better results at this time. Stem splitting technology is continually advancing so whoever is leading the pack today may not be the leader tomorrow.

One additional point to make regarding the Band-in-a-Box stem splitter. The BiaB automatically aligns the stems with the master. That saves you some work.

Jim Fogle - 2025 BiaB (Build 1128) RB (Build 5) - Ultra+ PAK
DAWs: Cakewalk by BandLab (CbB) - Standalone: Zoom MRS-8
Laptop: i3 Win 10, 8GB ram 500GB HDD
Desktop: i7 Win 11, 12GB ram 256GB SSD, 4 TB HDD
Music at: https://fogle622.wix.com/fogle622-audio-home