I would recommend that you upgrade the source first, the Sony 333es.
If your amp has enough power for your speakers and your needs, then I agree to look further upstream. I'm a fan of the DAC1. I don't know anything about your preamp, but if impedance matching between it and the amp is up to snuff then look elsewhere. You could also consider a room correction device. That might be the best investment.
IMHO, and at the risk of telling you something you already know, once you've reached your level of components, and especially since your're not considering a speaker upgrade (and I'm not suggesting that you should consider it), the only way to tell is to demo a piece--source, amp, or otherwise--in your home w/ your equipment. Beware of assuming that a newer, more expensive component will give you an upgrade in sound.
I must admit that I am not a firm believer that significant differences can be achieved via the "right" cables, power cords, and power supplies. It seems like most folks responding to this post suggest upgrading source and amp first. I have taken the first step, and added a DAC right behind the Sony SACD 333ES player. My impression is that that the music improved in clarity and crispness, particularly in bass and mid range representation. I will look around on the Audiogon boards for a good amp deal. Thanks to all for taking the time to help me.
I owned the ST140 some 15 -20 years ago. I owned the Khorus speakers about 5 years ago. You need a better amp - pure and simple. Updating your source to a better dac would also be a must.
No mention of how much money you have? You can get an awesome DAC today very little money. I think you can do both instead of paying what you might be considering for one.
Get an Oritek Audio modified Zhaolu D2.5 dac for $599 new. It is an absolute giant killer. You can use your Sony for a transport. This DAC is amazing and outperforms dacs cost up to 10X more! You can also sell the Sony and use an Oppo for a transport.
For the amp I would stick with a nice SS or Hybrid amp to control the bass on those X speakers. I own an ART Audio SLA2 that costs only $285 new and it will smoke the once wonderful ST140. This is 200 watts per channel. I can share more if you are interested.
Your speakers can use more midrange and the Monarchy SE160 mono amps would be great for some $1200 or so used. A used Belles Ref 150 ($1400) is also a great amp with better high and bass then the Monarchy. The Monarchy wins out out for mids and wonderful warmth.
I think it gos a little beyond a simple cable upgrade,a decent conditioner can do much more for a system than a next up cd player or amp.Having that right youll hear just how good that gear is or isnt.I used to say that it was money that could be used better.The building blocks to start with got to be there.Thats my veiw like everybody elses two cents.goodluck
Grannyring, you are so right. Ironically, I put a Zhaolu DAC behind the Sony CDP. I learned about it from Head-Fi.org, another favorite site of mine. Wow, that is so cool that you also owned the B&K ST-140 and the Talon Khorous X speakers. Mike Farnsworth of Talon Audio took care of me and re-did the cross-over network on the speakers. I was sorry to hear that he had trouble with his business and sold. I will follow the broads for the Monarchy amps. What makes them so special when mated with the Talon's? I find the Talons to be heavy on bass and mid-bass. You didn't find that to be the case? I thank you for your insight.
They are heavy on the bass as your amp is slow and not controling the woofers in your speaker. A Belles Ref 150 amp will take care of that while the Monarchy amps not as much. The SE160's will control the bass far better then your ST140 however.
I did find a little midrange suckout in the Khorus speaker that the Monarchy amp match well with as the amps have a rich and wonderful midrange.
What is more important to you - better bass control or more midrange presence and treble smoothness. The Belles is also smooth on top and more transparent than the Monarchy. I just think the Monarchy amps have a wonderful tube amp sound without the hassle of numerous large output tubes.
Both amps are great, but your sonic goals are most important.
My power seems clean with the EP-2050. I cannot say I had an "A-Ha!" moment after it was installed, but I'm comfortable knowing there's real science and engineering behind the product, and that it's protecting and filtering the power throughout my home.
Another user utilizes the EP-2450 Home Theater unit in addition to the EP-2050 and likes the results. I remember being told by Doug Joseph at Environmental Potentials that this was the next step if I wanted additional filtration at the system level.
I presently use an Alan Maher Reference Power Center V2 with the components, but frankly I do it more because the RPC V2 has eight outlets that I find useful. I could easily live without the additional filter unit.