Vocals vs. Instrumental. Cheap Rotel vs. Aragon???

I have recently been doing a lot of AB'ing with my friend.
He is newly into quality sound.

Music used for comparison was Natalie Cole - "Unforgettable"

The mix of pertinent gear includes:

B&W 802 Series 80 Floorstanders
Aragon 8008ST 200W power amp
Monarchy 18b DAC/Preamp
Home depot speaker cable

I have:

B&W P4 Floorstanders
Aragon 2004 MKII 100W power amp
Rotel RC-995 Preamp (upgraded PC)
Rotel RCD-971 (upgraded PC)
Rotel RB-981 130W power amp (just arrived today)

IC's used with both systems:

Ecosse Conductor
Signal Cable Analog2

Other cables used:
Homemade CAT5 biwire speaker cable (the winner by a long way)
Biwire - not mentioning the name (no good in my setup)

Various very high end cables used at friends house.
Also auditioned a Pass Lab Aleph 5 at friends with 802's

What sounded best I hear you ask?

Well the Pass sounded best at friends, but my Aragon 2004 sounded much better than his setup (same source RC-995/RCD-971 used throughout)

Tha absolute winner IMO was the rotel RB-981!

My system (B&W P4's/RB-981) sounded better compared to ALL the other amps/speakers combos, how can this be?

My speaker cables make a big difference I know, but how can an Rotel RB-981 beat out an Aragon 2004 MKII + 8008ST and the PASS class A????

I think I know the answer, the little Rotel favors vocals over instrumental and seems a little warmer IMO

The Aragon does seem to have more finesse but just does not sound as "musical" and definitely not as foot tapping.

Aragon: Instrumental seems too forward in relation to vocals, the little Rotel (130W) whipps the ass of the Aragon 8008ST/2004 MKII in my system.

And my cheap sytem sounds better in any configuration than my friends 802's/8008/Pass Labs!

Can this just be speaker cables or is there more to this such as room synergy?

Anyhow the Rotel sounds amazing perhaps a little grainier than the Aragon but 100x more enjoyable...

What's going on??

Cheers,
Josh