This is another great area to focus on. Similar to the female vocal in that we all know what a vocal should sound like, the range is completely different. In many cases the male range will be in both the bass and midrange area--a good test for the crossover and room acoustics.
Here are some of my favorites:
1. Harry Belafonte - Harry sings the Blues. Classic 45 RPM single sided is really fantastic. Almost like he is in the room with you. I particularly like the first cut on the album.
2. Jay McShann - What a Wonderful World. Groove Note. A medium tone and raspy voice. Not a refined vocal at all, more emotion in really feeling the song.
3. Lugman Hamza - with this voice. Another Groove Note record--and just as great. Very smooth and refined voice.
4. The Tony Bennett / Bill Evans Album. The 45 RPM Analog Productions re-issue is fabulous. Piano and vocals--the audiophile dream (or nightmare)
5. Andy Bey - Tuesdays in Chinatown (CD warlock album). Another very deep and raspy vocal--really pushes those lower vocal octaves.
6. Ray Charles and Count Basie - Ray Sings Basie Swings. Pure Audiophile vinyl. Well you can't beat the cast and it is a terrific re-issue.
Well, as always I hope these recommendations are useful to you. Isn't this what it's all about--enjoying the music.