Looking for 50-100 watts of Tube Power (give or take) for my JBL 4349s

I have Altec 19’s... so somewhat similar to your JBL’s.

Of the suggestions above, I’ve owned the Quicksilver KT Mono’s and the VAC 70/70 Signature.

The VAC 70/70 Signature is one of the best amps I’ve owned with regards to sound quality and overall appeal. It’s outstanding with jazz, classical and vocals... but probably not hard rock. It is an older amp and repairs would typically require shipment to VAC, which is expensive and time consuming (typically 6-8 weeks in my experience).

The Quicksilver KT Mono’s with Gold Lion KT88’s or. Tung Sol  KT 120's are a solid all around choice. They are very dependable and focus more on quality construction than aesthetics. Sound quality is very good, but not elite (like the VAC 70/70 Sig that retails near $20K), which should not be expected from amps in the < $5K range. They are an excellent value new or used and often get overlooked due to their utilitarian aesthetics.

I’ve also auditioned a new Line Magnetic 845ia. The sound quality was excellent and I really wanted to buy it.. but the transformers hummed and buzzed significantly, so I had to pass on the purchase.  In addition to the transformer issues I experienced, I don't think these would have enough juice for your speakers or musical tastes

While some scoff at the idea of McIntosh, I’ve owned the MC275 MKV and currently own MC-30 mono blocks. The MC-30's are wonderful from a sound quality perspective, but might be underpowered for your speakers.  The MC275 is very enjoyable and would pair nicely with your speakers and varied musical tastes.  As good or better than the MC275 are vintage MC-60 monoblocks... or MC-75's.   

As far as pre-amps are concerned, I would immediately snag either of the deHavilland’s currently listed on US Audiomart. I own the deHavilland Ultraverve 3 and it’s the best preamp I’ve owned in 30 + years in this hobby. Don’t let the low price fool you... these preamps sound fantastic and respond well to tube rolling, which allows you to tailor the sound to your liking.

Also... in my experience, power ratings have to be taken with a grain of salt. A vintage push pull amp with 30 wpc can sound as powerful than a new Chinese amp rated at 100 wpc.  Focus on quality construction, before looking at power ratings.

I have JBL studio speakers and my Conrad Johnson CAV45 S2 tube amp pairs REALLY well with them and sounds delightful.

The Audio Research 150 SE would be a nice choice, but I've always been under the impression that AR amps sound best paired with AR preamps in balanced mode.

Take a look at offerings from Aric Audio. I’ve owned the Transcend Push Pull for 14 months and it is excellent. With KT150 tubes, you get a stiff 65w of Class A in UL mode. It also takes KT120, KT88, and EL34 with respectively diminishing power. And you can run all in triode if you wish. VAC also makes excellent gear. I owned a Phi 300.1a for five years and still use a Phi Beta preamp, which is stellar. While I never had the chance to compare the 300.1a directly to the Aric, my aural memory, suspect though it may be, tells me I prefer the Aric. Sold the VAC but have no plans to sell the Aric. And it's a bargain.

OP,

ARC VT80 would be a great choice over the older but more powerful REF 150. It has auto biasing and more updated control on the tubes.