Would Totem Arro's be a significant upgrade from Kef Q150's

As commented by others, and having owned multiple Totem speakers, the amplifier used to drive the mains is key to get the most out of them. Your room shape is interesting, and with the Yamaha A-S501 you could try it, see how it goes and with your room shape. Streaming Spotify Premium also leaves some missing top-end and air [imo] which may bring a little more bottom end as a result.

If you try this, let’s say If you are not getting the low-end weight you want from the sound [and you don’t go for a higher current amp than what you have now] - another option might be to add a Totem Kin Sub later on as an alternative approach to bring in the bottom end re-enforcement. Fwiw, I tried 50w, 100w, 150w, 200wpc amps with my former Totem Model One Signature speakers, and once a higher current and higher quality dual mono SS amp was in place did I get the real bottom end out of my Totems. Not as good with my weighty 100wpc tube amp at the time, needed the 200wpc 75amp SS amp to make the Totem’s sing their best. This is why I mentioned the Totem Kin Sub as a sideways option too. Best of Luck.

@immatthewj decooney,, did you ever drive the Totems with your V12?

Yes. Apologize for the long answer. It was a pivotal point for me about "speakers" at the time, fwiw. Yes, Cary V12R tube amp. Cary SLI-80 tube amp. And, Cary SA-200.2 solid state amp, all around the same time. Also had a few loaner tube amps at the same time just to make sure I was making well rounded comparisons. Also had a few other manufacturer demo speakers I was asked to evaluate at the time, along with additional pairs I was testing with audio and home theater at the same time too. All the sudden I was rotating in every amp and speaker I could get my hands on to compare to. Some of this was a bit discouraging because I really wanted to keep my mighty Totems.

The 4-ohm 87db Totems did their best with the more powerful SS amp at the time. Sure, they’d play on the tube amps, but a more subdued result, when compared to the big 87lb SS amp was 350wpc at 4ohms. This was a good comparison lesson.

I later compared all amps again with my custom designed and built 92.5db 4ohm speakers which did very well, and notably better at low volume level listening.

Disclaimer: I do a lot of low volume level listening comparison testing too. This might be a bit "unfair" to some folks who just say "turn up the volume a little more". Dont ask why, but I seem to prefer lower 90-93db more responsive speakers at lower volume levels. Just something I prefer. And, I did NOT get a chance to try any of the later model 8-ohm or minimalist crossover-less speakers that Totem started making that were "supposed" to be more tube amp friendly. I had moved on by then, fwiw. This reconfirmed for me what good or better speaker matching was about, and for me always seems to be a chore.

Hey @immatthewj wait a second. I just kinda realized something looking back at other threads. So you have the standard Cary V12 or V12I amp then now?

Before you try and test any more speakers, there could be a whole separate thread on what caps and tubes you have in your preamp and your amp now. Gotta tell ya, I drove myself crazy with my former V12R until I made upgrades, and this changed everything downstream for the speakers. Speakers reacted differently. Like, I’m saying, maybe a whole separate thread and i’ll pose two questions. Maybe take it over to a V12 thread or something as I can’t reply to msgs due to Agon fees, CC.

You can send me a msg, with these answers, and I’ll have to send a separate message later to reply back - separately.

Amp: Is the V12 all stock, and does it have the old original gray looking AudioOne coupling caps in it now? [if so, its time for a change, no doubt]. What front end EL84s do you have it it now, what brand/model/era. Same goes for 6922s etc.

Preamp: Do you run the SLP-05 preamplifier now [or am I confused]. Exactly what tubes/model/era are you running in the preamp now? [if running the new Tung Sol tubes, they are smoothed over, kinda veiled over, not good in my Cary SLP98]. I run other TJ Full Music there and just received new PSVane Art Series II 6SN7s direct from the factory and testing those soon. Opening box in just a bit, fyi.

If I’m remotely close to these other assumptions, its definitely worth a serious look here first before more speaker buys imo, and fwiw. Before I upgraded my V12R, it was a bit more flat and dull sounding. After the upgrades, it was truly amazing. The new owner was astonished at the sound, he also compared it at his friends house against a very high $ Aesthetix amplifier and both said my upgraded Cary V12r surpassed the sound of the Aesthetix. They drove it hard I guess, even with massive electrostats until it ran hot for weeks I guess, and had a transformer meltdown or something  The only thing upgraded in that V12R was the coupling caps and the smaller input/driver tubes up front to very nice matched vintage tubes. If you want more open and large sound with a V12, this will do it. Send me a msg with the answers fwiw.