Single ended = large images?

@montaldo fwiw, I came from four different Cary amps [triode/ultralinear) and did the whole DH Inspire Hot Rod Triode thing for a while too. I mention this because I see you run QS V4s with KT150s. My current amps [now upgraded] are the QS M120s originally designed for KT150s, now running KT120s. Thankfully. I evaluated and changed the triode input/driver tubes first, and then upgraded the QS amps to the exact same Mundorf Coupling Silver-Gold EVO caps I ran in the former Cary amps. Bing! Personally, I don’t care for the coupling caps or the main power capacitors in the signal path that Mike runs in the larger QS amps. Spending up here for really good ones here helps, notably. Others will confirm this who’ve done it. Several others here have made similar changes [particuarly those with speakers less than 93db]. FYI, he uses big efficient horn speakers for his design work btw, and possibly those silver cables too, hmmm. This might be the cap gap debate with different use-cases and speakers like yours and mine with lower sensitivity and efficiency. With these upgrade/changes, I now like my QS amps better than any of my prior Cary or DH Inspire triode amps prior. The sound stage, depth, height and focus is just right. Not overly large or ehco extended, nor anything like that. Not at all. Sits in front and spaced apart accordingly and stage depth now where it needs to be imo. I know what you are talking about btw. This is something I was looking for too fwiw.

Wanna try something else instead? - Find a good local tech, get those V4s upgraded and you might be surprised. Some members here emailed me back doing the same - reporting amazing results too fwiw. My KT150s are stored btw, the KT120s are really nice after the caps get swapped out and some good interconnects used. Take it all with a grain of salt I guess. Best of luck.

@montaldo sure, I started with KT150s in my QS M120s. They have a little more top end and a little more bottom end compared to the KT120s. I came from Cary, EL34s and Triode amps too. For me, I will always favor that EL34 midrange type of bloomy sound vs something more analytical with just more detail and more bass. Mids for me is where the music is at. Guitars and Piano keys gotta sound engaging. I was never going to be able to find enough power with 300B amps. Cary FE 211s are massive amps, high voltage room heaters. If I had a large separate room, with more AC - I might have gone that route or maybe not.  Too big really.  Mike’s smaller QS Mid Monos with EL34s are short on power and drive for my particular custom 6ohm 92.5db speakers I built. So, Mike and I talked. He felt I might like KT120s more. Started going back through friends with CJs. and the CJ forums, they like the KT120s there too. I later realized KT120 might have been closer to what I like. Af first I did not like them. Tried them twice in fact. Next I then let them settle in about 100hrs and realized it was headed in the right direction. I had played around [a lot] with the small input/driver tubes on the QS 120s, similar to how some of the V4s are set up. I have the other EVO Silver-Gold non-oiler caps. Exact same ones Cary uses on their top shelf upgrades on the FE 211s and such. The KT120s paired with vintage 1960s era Mullard 12xx7 tubes or PSVane 12xx7s up front sound nice. Particularly so when paired with the upper end Mundorf caps. When the amp transformers get warm and saturated, the 3D layered effect occurs, sounds in front, across the front, up to the sides of me. One of my former Cary amps did that too with the same caps, but the QS M120s are cleaner sounding now after these mods. The amps transform with the right caps/tubes in them. 

@montaldo its worth checking what you have inside first. There was a batch of guys who saw my first post about 4-5 years ago and tried them in the M120s and the V4 amps. Cannot say I recommend it unless you have a lot of patience getting through the ridiculous settle-in time on the caps I have. Check yours first to be sure.

Mine are in fact the Supreme Eco SilverGold Black SESG Series Metalized Silver Gold Polypropylene Axial, SKU: Mundorf-80510, MSRP $59.88 USD each

The REASON I went to these caps in my QS amps is I wanted to confirm how much of the sound that I was hearing from my prior upgraded Cary amps was dictated by the sound of the coupling caps alone. Sure enough, caps matter a lot. 

The downside was just how freaking long it took for these particular caps to form and settle in. Good grief.   I was pre-warned by a retired local tech friend about this on the first set of Cary amps. He was spot on.  Told me to "get ready for the roller coaster ride", and yes it was nerve-wracking at times  Both Cary and QS amps took 300hrs before things stabilized and the sound and presentation stopped changing.

@montaldo along with QS V4 power tubes, upgraded coupling capacitors, those little front end input/driver tubes matter as well. What are you using now - brand, model, year:

1 - 12FQ7 input?
1 - 12BH7 or 12FQ7 driver?

@montaldo to help you save time, grief, and wonder just give Brent Jesse a call, and ask for the best measuring tubes he can offer for your QS V4s. I looked up yours there and they are not too costly.  He uses a real curve tracer for testing for matched triodes and such. If only I had met Brent decades earlier, could have saved myself and others lot of time. I am currently using mid 1960s Mullard Blackburn plant 12aT7, 12aU7s in my QS amps. Yours appear to be 12FQ7 and 12BH7. The key is quality tubes, low noise, balanced. I compare mine with other vintage and re-issue some times. Brent's best offerings are extra nice. If you like them, buy a set of spares and enjoy.  Call him though for your first inquiry and ask him to help educate you a little. It's worth  the time and $. You might end up hanging on to your amps long term if you go through these steps. Best of Luck.   

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