@justvintagestuff
Thanks, Eagles - The Long run is a super album for listening and also testing e.g heavy drums and bass. They really made a SQ jump there. "I can't tell you why" is a personal test favourite for hearing the bass-line separated from the kick-drum and the other instruments.
John Campbells two albums are very raw with a natural voice.
The first song on Merritt Gibsons (@dbwalek) cd begins very natural (probably heavy processed :-) and the song "Area Code" has great voice and piano. Other songs too.
Just a few tips for natural voices Cassandra Wilson, Jill Scott, Cécile Vemy Quartet (with large scale acoutic bass), Nina Simone, Sophie Zelmani, Rebecka Tornqvist, Bo Kaspers Orkester, Angaleena Presley, Nikki Lane. The phenomenal Brandi Carlile ("The Joke"). Aaron Neville - Warm your heart - a must - audiophile recording. Terry Evans - audiophile recordings. Neko Case mentioned. Bonnie Raitts first not to forget. Most artists have some recordings that are very natural.
To really experience natural voices my advice is to get yourself a pair of very neutral pro monitors and to listen to them near-field. Like from 1 meter. The PCM Result 6 mentioned above I'm sure is a good start. Older PCM models could be bought for half the price used. For some change however, I've just gone back to passive monitors Westlake BBSM-4 and Audiopason Karis. Completed with subs. It's very entertaining to "see" into the recording. Be aware though that most pro monitors gives you warts and all...it's their job. But when it's good you hear the difference.