NAD 375 or NAIM 5i or NAIM Unite Qute

I inherited the following system:

Arcam alpha 7se CD player

harmon kardon AVR 120

b&w 303 bookshelves

monster power conditioner

It was an HUGE upgrade to what I was using before. Its been a joy listening to music again and exploring the new details and such. It's been 7 months and I've been thinking about where else I can take the sound. It's been fun to learn more about the hobby.

After researching and visiting local audio shops it's become clear that the HK is the weak link. I really only want a 2 channel system. No radio. I'm looking for advice and thoughts on amps. I'm thinking an integrated amp. Although I've never heard tube. These are the two amps I'm looking at now:

NAD 375 (new, $1200 + 13% tax)

Naim Nait 5i (used $850)

Considering Unite Qute

I want to get more out of my b&w's but I'm sure I'll want to upgrade speakers in the next year or two. So I want to be prepared for that with my next amp purchase.

A couple of other things that I've been thinking about is the whole tube option and whether I even want to go down that route. From what I've read it's a warmer sound , which sounds interesting to me. But more money and maybe more maintenance.

Secondly, high res music. I don't currently own any but wow I heard it at one of the shops and I know I'll want to get into that. Should I be considering that in my amp purchase?

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My music tastes - from Zeppelin to Elvis, vocals, acoustic, soul, blues, classical , hip hop.

Interested in live sound, 3d imaging sound stage, non fatiguing , joy of listening, soul moving.



Thanks in advance!!