Conrad Johnson Classic 120se vs. Linear Tube Audio 40 Reference Amps

@bluethinker a question above is worth answering to, i.e.  "you need to decide how far off the neutral center you want to be."?  I agree with @cellorover's question and notes on KT150s. You've already commented hearing the Art 150s in your system, and not liking them as much as your own Qualiton amps, are those the ones with EL509s?  

Having owned different amps with KT150s, KT120s, and EL34s, and you hinted at EL34s, imo they can be at the opposing end of the "bloom" spectrum of KT150s (are more neutral), KT120s (midway, slightly rolled off highs), and EL34s tend to have more rolled off high freq, more pronounced ("bloom") midrange body (more lush) than more neutral KT150s - generally speaking.  However, it truly depends on the amp circuit and associated coupling caps used, for starters. Each of these tubes can sound different in different circuits.@jjss49 already referenced older CJ sound vs. the newer and more modern CJ sound, which is spot on. Here are a few questions you partially noted, and sharing them back with you, with a few twists: 

1) What's your budget limit for a "backup" amp to rotate in once in a while?

2) Are you looking for a second amp as a backup -or- possibly a full replacement to your Qualiton 100w amp altogether? 

3) Are you hard pressed to keep the LTA MicroZotl preamp? (i.e. not that its bad, however its influencing part of what you are hearing when trying other amps).  

If you are truly serious about considering CJ:

Personally, based on your descriptions so far, 87db speakers at 8ohm, I'm thinking you might like EL34s. It will soften things out with your current preamp, imo.  If Conrad Johnson, possibly the Classic CL120 (non-SE) version with EL34 tubes, if you want a newer amp from CJ. Expensive though, for a "backup" amp.  @jjss49 's suggestion to look at older CJ amps may be a more viable option from an affordability perspective. Or, for something lower cost, maybe pick up a used Dynaco ST-70 with EL34s (til you get your Qualiton amp back), something to rotate in once in a while, and you do have 8ohm speakers, more tube amp friendly.  However, the ST-70 will seem underpowered compared to your 100w Qualiton. 

Other:

For any reason you think you might part with the LTA preamp or the Qualiton amp later, its worth possibly deciding some of this first before making any moves, imo.   

Hi Everyone - I appreciate all the responses. Sorry for such a belated reply. After demoing a couple of amps in my house, a rogue hybrid tube/class d amp that was acclaimed by a dealer here in Portland, and then a PassLabs xa30.8, I decided to pull the trigger on a used Conrad Johnson classic 120. Have I heard it? No. 

I decided to go with my gut. Many of your comments helped me with the decision. I also found a video of the classic 60 online and it had the sound signature I am looking for. 

It’s not a neutral sound I am after. I am looking for second order harmonics. Fuzz! 
 

I’ll report back once I’ve got the amp here! 
 

OP,

Congratulations. Look forward to hearing your impressions. I suspect they will be favorable. Sometimes the right approach is to eliminate options and to go for what is left.

@ghdprentice - Thanks! I’m looking forward to hearing these EL34 tubes. The deliberation period was extensive, but ended up going with a gut instinct. Comments from those here on this thread were very helpful. 

@ghdprentice @decooney @lancelock @jafant @marco1 @paulcreed @jjss49  @cellorover 

I realized I never reported back after pulling the trigger on a used Conrad Johnson Classic 120 using 8 EL34 tubes. 

The verdict? 

I could not be happier with the choice. The synergy of the CJ power amp and LTA Microzotl preamp is wonderful. To my ears, the less expensive CJ classic 120 sounds better than the CJ Art 150. It must be the dig fence in tubes. The EL34 tubes have a relaxing and musical presentation that offers a subtle counterpoint tot the Qualiton/Audio Hungary 100 power amp that I switch it with. 
 

This hobby gets too expensive though… ended up spotting some NOS Mullard EL34 tubes that someone was selling because they’d sold their tube amp. When does the madness end?! 

Anyways, thanks to all of you for your guidance. Your collective feedback led me to exactly what I wanted.