change amps or speakers

@majorc
I’d get a good matching tube preamp no matter what. Tons of threads on this topic alone. If you do order a Linestage preamp from Mike at QS, heads up, for $50 upgrade service fee, he can convert the TapeOut to a 2nd set of PreOuts if yourdecide to bi-amp as others suggested earlier. Or, use the added pre-outs to add a really good subwoofer for added bottom end your mono 60s won’t have to make up for. A nice sub could fill in bottom end and let your LFT8s flow with KT88s in the Mono 60s. Add good tubes in Linestage preamp from Mike@QS.

Local Tech Option: 
You mentioned a local tech. Yes, a good local tech can also upgrade coupling caps in those amps to much better ones to add transparency you are looking for, along with checking tubes, re-bias. I upgraded my own QS Mono 120s with Mundorf Supreme EVO Silver-Gold caps, and the upgrade has been very rewarding. Yes, see your tech! 

Option-C:
Check this out. If you keep the LFT8 speakers, you could do the preamp now, add KT88s, run for 1-2 years. Then,wait for KT170 based amps to come out next! Yes, did not mis-spell. New tube coming from Tung Sol would be perfect for your LFT8s. :) Guarantee you’d love those LFT8s all over again with a bit more drive.
https://www.instagram.com/p/CG77jvZJEoH/?igshid=xj8re0i2fhl2

Asking again , are you making rated power with the DAC direct ?

A pair of Vandersteen Quattro are magic with Quicksilver amps, the original cloth versions are dropping into $3k range. I have heard 60 watt QS driving 5a, sublime... 

@yogiboy Do you have the older 60 watt Quicksilvers? Or the new ones?

+1 @yogiboy
Agree. This is an important question for @majorc to answer to first.

@majorc
FYI, my local dealer who’s carried Quicksilver amps and Eminent Technology speakers since the 90s shared to pass along to you today, quote: "the older mono sixties with smaller transformers running EL34 output tubes are power limited to effectively drive and power the lower efficiency 82db sensitivity EMT LFT8b speakers." He’s tried several amps with your speakers over the past few decades.

He also shared, The "latest design QS Mono 60s with the LARGER transformers and KT88s -OR- the QS Mono 120s with KT150 tubes -OR- a good 100wpc solid state amplifier would be a much better choice to drive your LFT8b speakers". He also shared a good matching preamplifier for a proper amp(s) is highly recommended.

Hope this helps...

@ majorc
 I have a pair of quicksilver amps, the silver sixty's, I use them to drive my 4425 monitors. And they sound fantastic. They are very dynamic amps. You have a great pair of amps. Amp and speakers should match. The 4425 monitors are 8 Ohm and their efficiency is 0.8%. They have great detail, they are neutral and very dynamic. You can play them at 65dB or 105dB and their composure does not change. With the 4425 20 watts is all you need. Also, your quicksilver amps have a gain of 25dB and need a preamp of at least 14dB of gain to drive the amps to their full sixty watt output. IMHO: I would try a preamp first, and if you do not like the sound look for different speakers. If you change your speakers make sure they are 8 Ohms or higher as that will make the quicksilvers very happy. I hope this helps.