Sound Quality After Win10 Upgrade

XPS 15 (9530, Late 2013)

NVIDIA Virtual Audio Device (WaveExtensible)(WDM); Realtek High Definition Audio sound card

updated to Win 10 yesterday. Used Dell Support site to update necessary drivers (6 needed updating). Also updated system BIOS.

Sound quality using the Windows 10 player (Groove Music) is good. Sound quality using all other players is terrible (iTunes, Music Bee, 1by1). The sound is muffled, too much bass. Sounds like a poor AM radio.

Dell system test shows everything working. Device manager shows devices are working properly and drivers up to date.

As I said, all drivers have been updated.

Any ideas?  Thanks.