Thinking about upgrading, but wondering about diminishing returns

Hi folks,

I have mostly Conrad Johnson Gear-- LP260M SE mono blocks, with 8 kt120 tubes each.  These are SET amps that put out 270 wpc.  I have the Conrad Johnson  ET5 preamp, with a Telefunken 6922 tube, and a pair of EgglestonWorks Viginti speakers (their new take on the Andra's).  Phono stage is the Pass Labs XP-15.  For source material I have a Rega  RP10 with the Apheta2 cartridge, and the Oppo BDP105 (Modwright upgrades) CD player.  I have Audioquest Colorado interconnects (go easy here :) ) and Audioquest Oaks for speaker cable.  My listening room is 13 x 19, carpeted floor, drywall walls and ceiling (well insulated).  I set up with the equipment on the long wall, with me listening from the 13' side (with speakers in about 2 feet and about 8.5 feet apart).

I listen to a mix of vinyl and cd's; vinyl when I have several hours to listen quietly (and clean the records on the Clear Audio Matrix Pro Record Cleaning Machine).  I listen to CD's when I have less than an hour, and for when I work out.

I am thinking about upgrading a single component, probably my preamplifier, to a Conrad Johnson GAT2 or a Pass Labs XS preamp (solid state). My thought was that this will likely make the most improvement in soundstage, imaging and overall musicality.  A used GAT2 will be at least $14K and the Pass XS used is about $19K.   I am interested in hearing from those who have had experience with upgrades like this.  I am also wondering (as a middle class guy)  how close does this come to the law of diminishing returns?  Finally, is this the component you would upgrade, and if so, if you had a wide range of musical tastes-- mostly classical/full orchestra in vinyl and rock on CD's, which preamp would you select?

Please feel free to take a swipe at these questions, and also feel free to point out if you feel I should be asking different questions that will help increase my knowledge and advance the cause for others.

I am likely to go to an audio show sometime, but please don't suggest that I go and listen to the gear, as that's at least 200 - 400 miles, and I don't feel right about going to a brick and mortar store knowing that I will almost surely buy used.

Thanks in advance for whatever assistance you can provide.

Ag insider logo xs@2xliamowen
We all have different ideas about where the set point for "diminishing returns" sets in. That said, I can't over emphasize how useful I found it to spend the time and money to go to an audio show and spend three days listening to a broad range of equipment at various price points. It really helped clarify the places money would be best spent in my case. It certainly furthered my sense of wonder at how varied audiophiles are in what appeals to them (and made me realize the suggestions one receives on these forums are quite "varied" in applicability to my tastes.) I would suggest that if your living situation allows consideration of acoustic treatments for your listening area, that is also an area that will provide improvements disproportionate to their cost. Good luck in your quest. 
A SET amp with 270 watts? That can’t be possible!
The input signal is amplified by a single-ended triode amplifier designed for wide band�width. The signal is then direct coupled to a cathode coupled phase-inverter. This high cur�rent, triode phase-inverter stage provides a bal�anced, low impedance drive to the output stage. Output power is developed by KT120 power tubes (two pairs per channel in the LP125sa, four pairs in the LP260m), chosen for their excellent sonic character, high power capability, and reliability. The output tubes are operated in ultralinear configuration which offers a desir�able combination of high power and low distortion. Massive output transformers with intricately interleaved wind�ings afford extended bandpass and high phase linearity. A small amount (about 12 dB) of loop negative feedback reduces distortion and achieves a sufficiently high damping factor to control reactive loudspeaker systems.
I think you should go to an audio show before you buy anything.

I would also suggest that a different turntable and cartridge may be a better place to upgrade
Upgrade your sources first.  Start with the cartridge and and the CD player.  Nothing is wrong with them, although the Apheta has its detractors, I just believe their replacement would provide you the most cost effective path.
In my opinion, you have a rock solid system and the law of diminishing returns is a killer. One will have to spend a lot of money to hear a bit more soundstage, imaging, and overall musicality. I'm guessing that's what you are after by your post. I honestly am not sure when all is said and done that the switch in preamps is going to make that much difference. As Audiophiles, many of us (myself included) get bitten by the upgrade bug not that there is anything wrong with that.
I'd be curious to know if you are using dedicated circuit breakers and upgraded AC duplex outlets? In not to me that comes forst.
Sorry if my initial comments seemed terse.

You have a system that looks like it sounds great and probably does. You are also in an area of significant diminishing returns. I have been in a similar situation and it seems like you can churn through equipment while making little if any positive improvement.

In your position changing to a better preamp will make an improvement, but the change will not be really significant because of diminishing returns.

Because you only listen casually to digital I would not spend much time or effort there.

I would focus on my analog front end. Rega makes a good turntable and you have their best. Changing to a idler, direct drive, or high torque belt drive (i.e. Dr. Feickert) will make a real and significant change to your system. I have had Rega, Michelle, Basis, and a lot of other turntables. Changing to a vintage Garrard 301 made a real improvement in my system. I think you should give a high torque turntable with a quality tonearm a try. I don't think you will want to go back.

Best Regards,

Jim Perry
Jim, your initial comments sounded fine to me, as do your others.  I appreciate your taking the time.  I thought about a Dr. Feickert before I got the Rega, and may explore that further.  Meanwhile, thanks so much for your VERY helpful comments.

Photon46-- Thanks for the room treatment suggestion.  I don't have any now, but certainly could add some, as this is a listening / home office / workout room (with a couch, ottoman, desk and cross trainer.  I must admit, though-- I have no knowledge of room treatments at all-- what is most likely to be the best bang for the buck improvement given the info I have provided so far?

Thanks everybody for the input so far.  Please continue to weigh in.  It is really helpful to me-- and thanks to George, who suggested that I put this on the forum in the first place.
'Diminishing' and 'Returns' are highly personal and subjective. No one, and I repeat no one, can assess that for you. It's your 'Law' to make and live by.
Thanks David.  I understand that it's my decision, but being middle class makes $15,000 A LOT of money for me, as I suspect it is for at least some others.  Maybe I can rephrase this as "what's the best bang for the buck" if I want to get a better soundstage (depth and instrument separation/definition) given the equipment that I have.

LAK-- I don't have a dedicated circuit, nor do I have upgraded outlets.  That would be easy to do, though, as my best friend is an electrician.  Is this upgrade generally viewed as helpful by the guys (and gals) with an electrical background?  Again, I have no experience in electricity, other than getting shocked as a kid, and making sure I have no static electricity in my system when playing.

Thanks all.
Honestly you have a ways to go before you should even think of upgrading your electronics. The Audioquest Cables you have are not up tothe rest of your system and your digital should be way better than it is.

We were long time AQ dealers we have since moved on to the Wireworld cabling which we think sounds even better for similar pricing. 

The Colorado didn't sound anywhere nearly as good as the Niagra which didn't sound anywhere as good as the Skys.

Also what are you using for power cables and a conditioner? Room treatments, racking and vibration isolation.

1: Upgrade cables
2: Add power conditioning and power cables
3: Vibration isolation for table and gear
4: Possibly better digital source

Then and only then would I even consider upgrading your preamp the ET 5 is very good, yes the GAT is even better but until you work on the envionrment first you will not gain the benefit of the GAT.

Also we have a set of ART amplifiers for $11k that will outperform yours you may want to make the swap before the preamp.  If you sold your amps for $6k you would  only have to add $5k to get a much better set of amplifiers. The ART/Gat combo was famous, the ET 5 was a mini Gat.

Dave and Troy
Audio Doctor NJ
@liamowen You are welcome. 15K is a lot and IS a significant spend.

Your post is clear, as is.

Let me put it this way, if I had your system and I had committed to spending 15K, I’d address the power side and cabling before choosing a preamp. For me, based on my experience, addressing the box and line to your room, and then the outlet on will give you system wide impact.

This ’should’ exceed the upside delta of impact from a top level preamp, which the GAT 2 most definitely is.

Having said the above, the addition of the right preamp for any system can be sublime (something I have recently experienced)...and it’s hard to put a price on that. However, what I've suggested will only add to what a top level preamp will do for your system.

All the best with the direction you choose and the choices you make.
Great system as is, However the one way low item is the Oppo. I suggest the "one thing" you need is a better silver disc spinner. I would seriously suggest checking out the Marantz SA-10 ($7000 list) as a great device. Esoteric and PS Audio also make good silver disc spinners.The Marantz is particularly good with CDs. So if you play many CDs.. I would highly recommend the Marantz. (It is great used as a DAC too)  
One other area you do not mention at all is a Power Conditioner. I would suggest as a second item one of two choices. Either a AudioQuest Niagara 7000, or a PS Audio P20.
Small upgrade #3 would be a few high end Duplex, at the wall, and AC distribution if you do not buy a AQ or PS Audio device.
I think the amplification is great as is. Ditto speakers and TT.
great system that I bet brings a lot of joy...

by all means use the electrician friend to add a few dedicated circuits on the quiet leg of your panel. IF he is going to use unused breakers buy new ones from a quality company ( Square D ), hab
ve him clean up box, check grounds, tighted everything. You can get Hospital grade Hubbel outlets for $30 and then the sky is limit....IMO $120 buys a killer outlet.

Room treatments - Call GIK Acoustics and speak w engineering sales person, they will advise on room. w your size room you are looking at about $2k, maybe 3... this will make a WORLD of difference....

get Jim Smiths book on better sound. Revisit your speaker setup using a precision setup laser ( Leica disto ) your speakers reward careful detailed setup !

Power conditioning for digital components, switching supplies and trash and has producers first. Here a Furman can be quite effective. I like the Niagara class gear for phono pre, but not Power amps.

You can easy trial PASS gear including used and demo gear with return via the dealer in Colorado...great accommodation 

Used Sky interconnects validated by factory to be authentic would bring out nuances missing today.

have fun !!!! enjoy the music

@tomic601 , 
+1 as usual.
As an AQ user, I have great respect to their products.
Johnny Rutan suggested that I upgrade my Rockefeller speaker cables to GO-4 last year. I bought them, but never installed them, as things sounded really great and installing new cables was a PITA. But, we got a new rug and things had to be moved, so while doing all the moving, I installed the GO-4's.

Reconnecting the system, even my friend, who thinks I am crazy buying all this stuff said:
'Wow, what a difference. Bass is more articulated, things seem more alive, and I thought is couldn't sound better. Even before Billie Holliday seemed to be in the room'.
So, I think you should consider at least a cable upgrade, before spending a lot of money on a new component. You might be surprised.
Johnny's Agon name is Audioconnection, should you wish to PM him. He won't sell you, but will give you honest information.

 I also second having an electrician install a dedicated line to your system.
Are you bi-wiring with two pairs of GO-4's? John Rutan called me and suggested the GO-4's. I haven't tried it yet. I still have a bi-wire pair of AQ. Rocket 88's. Guess I better GO-4 it! lol....                                            Tim
Yes, Mr_M, two pairs.
To be honest, I thought the Rocket 88's were the cat's meow, but Johnny said try this, and I did. He also recommended the AQ Thunder power cord for my DAC (Ayre Codex). I ended up putting them on my amps, and I can honestly say they made a huge difference over the no name PC's that came with my equipment. 
Mind you, I own both Ayre and Atmasphere. Ralph seemed to dismiss a power cords ability to affect sound reproduction (if I recall correctly, if not, forgive me Ralph), and I have read that Ayre equipment seems to be very indifferent to changes in power cables (perhaps due to the zero feedback design- like Ralph's).
In any case, the change was quite dramatic. And, for the positive.

Let me state that I am not someone who buys the most expensive doodad. In fact, my system has been bought entirely on Audiogon and US Audio Mart. I researched as best I can, and picked John Rutan's brain. To my aged ears, I have a stereo I can listen to for hours on end, and can't find anything lacking- the music speaks for itself.
That being said, I hope the OP will give my posts some food for thought.
1. I’d definitely keeps the Oak’s as a finished system item then add either AQ Fire or Wind ic’s.
A substatial improvement will be gained using PSS vs copper. Huge. You’ll get more transparency and detail with smoothness. You will never go back. Niagara ic’s will provide you with a similar change for less money. I got off the merry go round with Oak and Fire in a very high end system. Properly done silver is fundamentally superior imho. Zero brightness. 
2. try a very good dac with the oppo for another major upgrade. Demo the Mytek Manhattan if you can. Both with the CJ pre and direct without. 
Both of these upgrades will be money spent that will be very meaningful. Start with the ic’s imo
OK here is my 2 cents worth. If you want musicality then the Pass preamp is kind of not going to do what the CJ preamp will do, SS versus tube. BUT you are not asking for that much to begin with. Opening up the sound can be as easy as changing preamp resistors to Caddock, naked Vishay or Shinko (very musical) all for about $25 in cost plus installation. If you want to make a major improvement then you need to upgrade the phono stage and the DAC. But that will cost you big time.

Liz wrote Id seriously suggest checking out the Marantz SA-10 ($7000 list) as a great device. Esoteric and PS Audio also make good silver disc spinners. The Marantz is particularly good with CDs.

My opinion differs significantly.  The Marantz to me is an average CD player.  I have a buddy who spent $3K or more and it still sounds just OK.  The Esoteric is more dry sounding than musical.  How do I know this, well a speaker manufacturer uses my tubed DHT DAC as the DAC to a $27K Esoteric CDP because he feels the Esoteric which sounds excellent does not provide the  overall musical experience he wants to demonstrate his speakers.  The guy with the modified Marantz also changed to the PS audio and has again moved on from there stating 

The (new transport and DAC in comparison to the PS Audio set-up he used I won't mention here) is open, has great prat, and dynamic with very good micro and macro detail. I think it is transparent and not colored. What it isn't is dry, thin, sterile, and fatiguing. 

Tonally, it sounds natural with nice texture and has some meat on the bones (which to me is how a lot of acoustic instruments sound) but still has bite when a trumpet is blown harder, IMHO.
 "I like it much better then my PS Audio Memory player and Directstream DAC combo" 

Not sure how helpful I am but that is what I can contribute.

Happy Listening.
It is nice to just change things up.             
Follow your Luci...Do It.  
Look into Room Treatments for sure spend $5000 there and you will be amazed...truly
Think about it, look at ANY legit recording studio, they spend big $$ building the rooms.
Good luck on your endeavor, bet that system is amazing!
Damn. Your way more middle class than me. I’m jealous. 
Donvito, according to Conrad Johnson, it is rated at 270 watts, into a 4 ohm load. 
Your amp and preamp are very good products. Your front end (cd player and turntable and cartridge) are significantly holding back your system. Even if you spend 15k, the low end or your budget, you can purchase a close to state of the art cd player (or transport and DAC) and turntable. You can also try different brands of cables from The Cable Co.
But I would do that after investing in a better front end. I can’t see spending more on an interconnect than the gear it is connecting. Furthermore, used cabling is a great deal. You can usually pay 45 percent of retail without worrying about damage from abuse to the item. After you get a new front end, sell your cables, buy better used cables and you will have maximized your investment overall.
Best bang for your buck is to paste all your connections with Perfect Path Total Contact enhancer ($299) or much less if you go in with a few buddies. Then get a Perfect Path Omega E-mat ($599) and put it in your circuit breaker box. Get 5 or 10 E-cards from Perfect Path ($299 for 5) and put one each under each piece of equipment. If you get 10 E-cards, tape one to the back of your top highest positioned driver and do the same with the lowest positioned driver in each speaker. If you have a large system, the PPTC may take awhile to do. I do and it took me about 4-5 hours--I had 216 individual pins to paste counting RCA pins, tube pins, spades, bananas, fuses ends, prongs of your power plugs and IECs. If you follow the directions and do at least what I said, in a day your system will be better sounding. The cool thing is, after you’ve done this there will be periodic jumps in performance especially at 4 weeks and 8 weeks. Adding the mat will bring very noticeable improvements to all things hooked up to the circuit panel including TVs, computers, and of course, your sound system. The cards have a quicker time to show improvement and will also make a big difference. All areas of your tunes will be improved. Perfect Path will be coming out with THE GATE that you will wire into the circuit board at 2 spots, much like a wires from your outlets. The Gate just sits on the bottom of the circuit box. It is said by the maker to being up to 100 times more powerful and effective than one mat. Of course, the price is much higher I believe. Tim Mrock of PP said it will be about $5000. He says it will be the single largest leap in performance by far that any of us have ever experienced. Pretty darn exciting. There is a long thread about PP products in the Forum. Spend your money on upgrades if you must. If you don’t experience the PP products, it is definitely your loss. I’m about to do the second and third stages I mentioned. One could buy and use more mats. They are more powerful than the cards. The cards can slip into smaller places, however.

Liamowen, you asked about where to start with room treatments. As previously mentioned in this thread, GIK Acoustics in Atlanta would be a good source for both advice and product in my experience. Their product line is a good compromise between function, aesthetic refinement, and cost. While there are product lines that have a more polished look to the finished install, they cost considerably more. I have ordered four times from GIK now. With each addition of more room treatments, the room I listen in has been further removed from my listening experience and the sound of the recording venue has taken on a greater proportion of what I hear. It's much better for you to communicate with GIK directly as far as advice for where to start. Every room is different and what worked for one person might not be the best place to start in your case. 
I would say you are way past the point of diminishing returns ..... unless there was s something in the music you don’t like ...... 2019 I am going to try avoid changing components .... maybe buy more music and see more gigs.
And to add I set up my larger lounge just for hifi so speakers placed purely for sound using cardas placement method they are nearly in middle of 7m long room. I then printed some pics from filming in Rwanda onto 3 GIK acoustic sound absorption boards for back wall .... also 2 free standing boards for 1 st reflection points. Would use bass traps in rear corners but doors and cupboards there so I leave them open with some drapes across to break up some rear waves.

speaker placement alone done properly is the biggest single improvement I ever made.
Wow!  Thank you all for your help on my original post.  Your responses have been very, very enlightening and helpful.

I am definitely going to go with a dedicated circuit breaker and some high quality outlets.  My electrician friend needs something to do this winter :)

I am also going to act on the room treatment suggestions, and the laser to make sure I have maximized my alignment on the speakers.

I will also do some testing with new interconnects.

Finally, I will check out a "better" turntable.  I am not sure what the rules are here about equipment, but if anybody has a lead on a turntable, or has one for sale, that will perform better than the Rega RP10, please PM me.

Sadly for the fellow selling the CJ GAT2, it looks like that's going to have to wait.

Thanks again for all of your help.  If anybody has anything else, please feel free to weigh in, either now or later.  I am still very much a novice at this endeavor.
"speaker placement alone done properly is the biggest single improvement I ever made."

Ditto, and cheapest as well. In particular, soundstage and image specificity most improved. In my experience, improving AC power delivery only helped with lower noise floor and slightly improved bass. No affect on what OP is specifically trying to improve.  
@laimowen, I can't emphasize enough the need for at least one if not two dedicated circuits (assuming they can be added bassed up your room location, whether you own or rent etc.) and an upgrade to a more high-end  AC outlet.
This suggestion will improve the sound of your music so you can really hear what your system is capable of. Those that have not done this are missing out on a very important tweak that can be inexpensive vs purchasing other types of components.
Other suggestions such as placement of speakers and room accustics are also right on target.
I listen to more digital than analog and my suggestion would be to consider a great digital transport like the Innuos Zenith III and a top notch DAC like the Mytek Manhattan. Then consider Roon and Tidal. The SQ will best your Oppo and you’ll have a world of music at your fingertips. 
Austinbob right on the money on old Denon is not up to snuff considering the rest of the gear this man has. 

Cables and new digital, a tube based dac might be nice to listen to the Mytek Manhatten is very very good, a bit on the clean and detailed side but over all a great piece.

Dave and Troy
Audio Doctor NJ
"I listen to CD's when I have less than an hour, and for when I work out".

Because of the limited time, an hour or when working out, maybe the OP doesn't want to spend the funds on digital, at least that was my understanding in his origional question.
@lak +1


I think you are on track with adding dedicated outlets and room treatment (look at the GIK website) first, then focus on a great analog front end.

Happy New Year

Jim Perry
One other possibility if you do not like the sound you are getting from the RP10 Rega is to change the cartridge? The RP10 has lots of great reviews.. I do not know what you could replace it with..But replacing the cartridge might solve any issue you have. The folks at Music Direct might be one place to talk about what you want that seems to be missing from your RP10 and offer a substitute cartridge?
Go spend $40 on Caig contact cleaner and enhancer, and afternoon cleaning, polishing, and enhancing EVERY connection in your system, and then $5k to my PayPal account for the advice. If you’ve never engaged in said activity, its worth the time and effort. 

Next, experiment with setup / room placement. That’s another $5k of advice. 

Take another $5k down to your local record store and go crazy. 

I know now we love to spend other people’s money, but reinforcement of the basics is sometimes the best advice. 
There is no law of diminishing returns in audio.

One rather inebriated passenger on a plane exclaims to another whilst looking out the window, “Hey, those people look like ants.” The other guy says, “They are ants. We haven’t left the ground yet.”
Like Dorwad said previously, I recommend the Total Contact product. About a half an hours work and I bet you will be surprised and probably amazed at how much improvement can come from one little adjustment. This is a slight bit more that a noticeable change.
Having read most of this thread, and seeing your substantial system, I would concur regarding room treatments being the best allocation of your resources.

I am married to a PhD Economist (Ivy educated - I do like to brag on her 😍) and our mantra is marginal cost versus marginal gain.

The amount of money needed to upgrade your electronics will never come back to you proportionally with respect to the money spent, great current system!

I have a different system in most regards: but respect your choices of equipment and would suggest that quality input sources and of course more spent on Music of your choice is the path to more big smiles!

Enjoy the ride and Never forget the music.
Possibly the most civilized, helpful and inspiring forum discussion I've read in the last few months (though admittedly I am a sucker for those click-bait posts). Appreciated.

Whole-heartedly agree with the suggestions you've picked up on so far. I will only add that in terms of imaging and sound-stage width and air, one of the biggest impacts I experienced was with the purchase of high-quality digital cables (Ethernet, USB and Digital Interconnects (Luna, Luna, Echole Omnia Cables respectively)). This was however after making all the non-component upgrades already mentioned. 

I use only a digital front end (TotalDAC) and was surprised by the impact-per-dollar value of these last-to-be-considered cables. If ever you get serious about your digital front end, you might look into this.

Also, can't speak highly enough about the pleasures of a great streaming set-up for musical exploration and discovery... its perhaps the most enjoyable feature of my system: being able to trial every piece of music that piques my attention and feel like I am hearing the full impact of the artist's intentions from the very first listen. So much surprise and excitement not knowing what music (and musical life) is around the next corner. Highly recommend as a way of extending the pleasure from your already great system from the sounds of it.

Enjoy and good luck.
@ihas.   ask her about utility function derivation....but hey my teachers are all Chicago school..ha

At this level, diminishing returns are sometimes just the tip of the iceberg. Sometimes you get negative returns. My system consists of (analogue source) Well Tempered Versalex / LTD2 tonearm / DPS power supply, Dynavector 20X2L cartridge, Pass Labs Aleph Ono phono preamp; (digital source) Naim CDS3, Teddy Pardo XPS power supply; (amplification) Naim NAC-112 preamp, Naim NAP-150 power amp; (speakers) ProAc Studio 140 Mk2. Cabling is either Naim or Chord. What I will say about this system is two things: First, the CDS3 is very well-regarded, and was the top of the line before the CD 555. However, my analogue front-end blows the CDS3 out of the water, despite having about half the price-tag. I’m certain that the reason for that is the magical Pass phono pre.  Stick with yours, it's going to be very tough to beat. Second, I’ve listened to systems that cost in the region of $240k, and don’t sound as good as mine at maybe 1/4 the price. Some of the really high-priced boxes produce a lot of hi-fi wiz-bang effects, but they don’t produce good music. Really the only thing that makes sense is to get a component into your system and see if it’s a synergistic match that really improves the music. Something may be higher-up the food chain, but may make your music sound too analytical to enjoy. And who knows, you might find that you get more out of room treatments than component upgrades. It’s all just stuff you have to try out.
"Upgrade" ... is a subjective thing ... and EVERYTHING has diminishing returns.

So you are correct to be concerned about them!
You should never buy ANYTHING unless you are :
1. Unhappy with your system, for a good long while.
2. Able to pin down what you want
3. Able to pin down what piece is the weak link and causing the issue.
Room treatments are a great idea. As a mastering engineer the room is huge ... and speaker placement is key. 1/4" this way or that can achieve huge gains. Then it’s the gear, which is also huge.  See 1,2,3.

Enjoy !
Hi liamowen, I believe that your 6DJ8's are a weak point. I have an AR LS15 which had V-Cap teflon caps bypassing the factory caps and thought I was done. Then I read about the Schitt Audio Yggdrasil DAC. I was so impressed with it that I bought their Freya, which with the right tubes, was a big step up, but that you need to blend tubes meant that something was less than perfect as neutral tubes should make it sound best, but it doesn't. That sent me to the Don Sachs DS2 preamp. Don spend decades upgrading HK Citation tube gear and McIntosh tube gear primarily. Then he found Roy Muttram's SP14 preamp, which he has spent several years improving. His DS2 preamp is neutral, and good 6SN7 tubes blow 6922/6DJ8 tubes away. They are just a far better sounding tube. As far as cables go, Cardas cables are about the best commercial cables I have had in my system, but honestly cables made with Dualund's improved version of Western Electric's tined copper cables. You can pick them up for less than $100 for SE cables, and perhaps $50 more for balanced cables. My AQ Colorado cables suck badly, but I can't speak to their higher end cables. That's where I would start though, as for speaker cables Dualund's 12 gage cables from Partsconnexion may be a little small for the power that you are supplying, so I would look at Western Electric 10 gauge cables, but there are now counterfeit cables out there. My source is now out of the 10 gage cable, so I can't tell you who may have the real thing now, it hasn't been produced in decades. The thing is though, for $100 or less, you can find out if I have a clue or not. Beyond the better cables, and the DS2 preamp, the Schiit Yggdrasil would likely be in the mix. I became completely frustrated with vinyl long ago. I had a Sota Saphire with a Souther liner tracking arm, and a hand full of other arms, Micro Benz, and other cartridges, but it was the PITA of dealing with vinyl that finally made me give it up. I was paying $50 or more for records that had more imperfections out of the original packaging than a $3.99 LP I bought as a kid had. I had multiple cleaning machines, but even when I cleaned the release wax off a new LP it sounded like crap, it didn't matter what arm, TT, or cartridge I used. I have heard that the PS Audio DAC sounds better than the Yggdrasil, but Schiit recently upgraded the Yggdrasil, and I have not personally listened to the PS Audio DAC. Other than that I don't know enough about the rest of your gear to speak intelligently about it. I hope you find your way to a system that you are finally content with!
Hierarchy of sound - A tweaked inexpensive system can be made to sound better than a much more expensive system that isn’t tweaked. Corollary - you can spend much more on Tweaks than you can on equipment upgrades if you’re not careful. 😛
Go to a brick and mortar store, listen to some gear, and develop a relationship with the dealer.  Buy from him/her.  This is a much better "deal" than buying something used with no warranty that you cannot listen to first.
I would change /add room treatments firstThen maybe new cartridgeThen maybe new turntable and arm.
 I would only mess with cabling if you had an absolute 100% return policy. Then I would make sure to remove any bias by having someone switch them for you so you don’t know which is being used. If you still perceive a huge improvement with the new then keep it otherwise return. 

 I think you have a great system, I wouldn’t bother changing your preamp the one you have is very good. And just to nitpick that is not an SET amp. 
Underwood Wally has the Marantz CD player on sale for $3999.00 delivered. I haven't heard it but people here say good things about it. I think you would spend more time listening to Cd's if your source player was better. I own an Esoteric X-01 and it's a superb player. I've owned the XO3SE and was very impressed with it. (It can be found when people are willing to sell it for close to $2000.00 used). Consider buying used gear. Your diminished return will be next to nothing. Good luck! Joe

Dedicated circuits, absolutely; they definitely add solidity to power amps. One for power amp, and one for everything else is more than sufficient.