Calling all Aesthetix Callisto / Io Owners

I have owned an Io (standard version with 1 power supply) for a little over a year. I replaced all the tubes in the audio chassis with Telefunken tubes and this was a huge improvement. And this week I took delivery of a Callisto (signature with 1 power supply).

1: Since I also have another line stage here (BAT 31SE) I would like to try both of the Aesthetix power supplies for the Io to see if I ultimately want to go with two supplies here. I would also like to try both power supplies in the Callisto to hear what is gained over just one P.S. But I see that the power cables between the PowerSupply chassis and the Io have different pinouts than the cables used to the Callisto. Are the power supplies interchangeable or are they pinned specifically for either the Io or Callisto?

2: Are there tubes within the Callisto that significantly benefit from tube rolling?

3: Has anyone done a shootout between the Standard and Signature Io? .... and what were the differences?

4: On the Callisto, when I move the "Right Level" control, there is a slight crackle/static sound from full attenuation to the first step and then again in the next 2-3 steps. From then on the noise is gone. I have swapped tubes between the L & R channels, swapped power cables between L & R, tried using a different set of inputs, swapping outputs to opposite amp inputs, etc. The problem stays with the right side. Does the right level control need to be "cleaned"?

Thank you in advance for any input here.


Do not try the Callisto PS on the Io.. if it is pinned diffently. Additionaly, you must make changes to the Io main unit (installation of jumpers) and changes to the 1st power supply internals for the Io to work with two power supplies.

I know because I just picked up my 2nd PS from my dealer yesterday for my Io signature w/ volume controls.

How will it sound with two PS?..well I heard an Io with 2 supplies over 1yr ago so my memory is not good... besides I could not directly compare it to a single supply unit. However, I'll be evaluating mine over the next while.

I'd email Jim white on this...Good Luck.
John, when I was purchasing my Io, I asked Jim White what differences he heard between the standard Io and Io Signature, and with and without the second power supply option. His reply as to what he heard was very direct:
The Signature provides the following benefits:

.. Greater resolution
.. More neutral presentation
.. Improved high frequency extension and detail
.. Greater top to bottom coherency
.. Better bass definition

Adding the second supply improves the sound in the following ways:

.. Added space
.. Improved macro dynamics
.. Improved micro dynamics
.. Blacker backround
.. Greater ease to the sound, less strained
Move the volume control back and forth rapidly for about seconds. It's probably just some dust inside.
Thank you all for your comments:

Nkj: It's unfortunate that the PS's are pinned differently for the Io vs. Callisto. Must be a subtle difference needed between the two products. But that ends my chances of hearing either one at the moment with 2 PS's. But thank you for confirming that this could not be done. I am eager to learn what comes of your 1 vs. 2 PS for the Io signature listening session.

Rushton: Good descriptions as to what should be expected. When I changed all the Sovteks to Telefunkens in the Io, interesting that I did not gain any of the benefits that you listed with the Aesthetix upgrades. But what I did get was a much more full sound in the mids with incredible decay of notes and presence. The last ounce of sterility was gone. And this change alone caught my attention as it was so incredible. Otherwise the Io's sonics were pretty much the same with the stock tubes.

I feel I could use a more coherent tonal balance provided by a little more extension at the frequency extremes rather than an increase in dynamics and reduction in noise provided by the 2nd PS. So it looks like a change to the Sig would be the ticket for me with the Io if I decide to keep it vs. the soon to arrive Aria preamp.

Tabl10s: Right on! I guess I should have thought of this as I have read many times that other people have had to do this. But this was the first time I had a volume pot that did this. And sure enough, I rapidly moved the control back & forth for a good 10 seconds or so, with the unit powered off of course, and now the problem is gone. Super!

I am so spoiled with the silky smooth control on the BAT 31SE and it's awesome remote that handling these huge clunky controls on the Callisto will be a very big change to get used to. But already the Callisto has a much more authoritative presentation and more energy on the top vs. the BAT. It is most impressive with the CAT amps. But what surprises me here is how well the BAT competes with the Callisto Sig at double the price. There are clearly many very talented audio engineers out there.

Thanks again.

I have a BAT VK-50SE, which I have been happy with for the price (having gone through many other units up to 2x the price). I am considering the Callisto but my main concern is the volume control. The BAT and other modern designs have many fine steps between mute and full output. How do you fine the volume control on the Callisto vs. the BAT? Ca you find levels suitable for quite listening? Is the range constant or with bigger steps at the low (greater attenuation) end? Finally, how quiet is it compared to the BAT? Thanks,
>"4: On the Callisto, when I move the "Right Level" control, there is a slight crackle/static sound from full attenuation to the first step and then again in the next 2-3 steps. From then on the noise is gone. I have swapped tubes between the L & R channels, swapped power cables between L & R, tried using a different set of inputs, swapping outputs to opposite amp inputs, etc. The problem stays with the right side. Does the right level control need to be "cleaned"?"

I asked Jim White about this and he said that the crackle/pop noise is normal.
>"I am considering the Callisto but my main concern is the volume control. The BAT and other modern designs have many fine steps between mute and full output. How do you fine the volume control on the Callisto vs. the BAT? Ca you find levels suitable for quite listening? Is the range constant or with bigger steps at the low (greater attenuation) end?"

The Aesthetix Volume Control has 46 steps that I believe are in 1dB increments. It is very fine and perfectly suitable for quiet listening.
>"2: Are there tubes within the Callisto that significantly benefit from tube rolling?"

Albert Porter has shared his experience on A-gon about tube rolling in the Callisto in the past (I think this was in 2003). Try doing a search, but he did find tube rolling to further improve upon the sound.
JaFox, John,

I'm going to clarify in suggesting that the Io supply should not be used with a different's an assumption on my part. However, I do know for certain that modifications must be done to the main unit and the power supplies in order to go from 1> to 2> supplies...logically each channel originally is accepting it's power requirements in parallel from one supply...after a 2nd supply is added each channel receives it's own supply. So some bridging must be used to make the adaptation. I have a copy of these instructions in Word format if you wish.

I just got back from Houston and I have not even taken the 2nd supply out of the box yet for a listen! it'll be some time before things get set up and I can make a report.

It sounds like you might be going down a different path with the Aria this will be an interesting comparison...I still have my Counterpoint SA2 all tube head amp designed by Mike Elliot and my ARC SP8 combination so I have some admiration for Elliot's designs....I guess I should get rid of all this extra stuff sometime. Is the Aria shipping?
Fmtien: Advice from Tab110s was just what the Dr. ordered. The noise when I move the right volume pot is now gone. Very happy camper here. Concerning the number of steps vs. the BAT, the Callisto is more than adequate for me but the BAT does indeed allow for much more refinement of level adjustment. I really like this aspect of the BAT very much.

And yes, I have paid a lot of attention to Albert's writings. But the focus has mostly been the Io which is why I was asking about the Callisto. I will have to go back and read more carefully his attention to the Callisto and the most important tube positions he suggests to change first. When I first got the Io, he wrote to me with great advice and the performance of my Io skyrocketed.

NkJ: Yes, I would much appreciate the instructions on multiple PS's. I am eager to hear of your listening results. And keep the SA2/SP-8. When I heard the SP-8 in 1982 (I remember that event so well) I heard music from a home system like I never did before. And no, the Aria is not out yet but I am eagerly waiting. I'll let you know.

Thanks much.

Jafox, here it is: I think that thread has been deleted but I saved a copy in my computers note pad.


Regarding the comments by Bud and Rayhall, the 6922 Sovtek would be my first change. For additional midrange and air, try the Siemens 6922 CCa or the Amperex US Military 7308 CEP. If either of these produce too much midrange presence, try the Mullard 6922 (gold pin). Realize, that when you upgrade to one of these higher resolution NOS 6922's you are listening with more intensity to the weaknesses of the remaining (original) tubes. You are judging the replacement, plus all that it exposes downstream. If after changing to the CCa or CEP, you find that there is too much "grit" in the sound, try swapping the 6SN-7 as described in my long post. After that, if you are feeling adventuresome, trade out the first stage 12AX7 tubes (Io only). Note, these 12AX7's are the ones I warned about, get TESTED, ultra noise tubes for this position. My first choice and the most beautiful sound is the Telefunken 12AX7. Other options are the RCA 5751, a US Military version of the 12AX7. The 5751 will alter the tonal balance somewhat, as it is not an exact replacement. There will be a slight loss in gain, with improved signal to noise and lower distortion. Overall, the sound will be a bit more on the dry side. One final suggestion would be the 12AX7 French Mazda. A good sample of this will produce significant improvements in high frequency transparency, especially compared to the Sovtek. However, the Mazda has not been without problems in my experience. The samples I received are not equally reliable or equally low noise. Some will play perfectly for many months while retaining their original "voice" while other samples will develop horrible microphonics and tube noise in as little as a week. This is a situation that could lead to disappointment with the Io, when in fact, the tubes are the culprit. Unfortunately, there must be some risk and experimentation within your own system to determine what is best.

Quick answer on tubes. If you have not swapped the EL 34 tubes in the power supplies you are in for a big surprise. Perhaps as big as the Telefunkens in the main unit.

I agree with what has been said about differences between regular and Signature models, the Signature has superior coupling caps which are a big improvement. Be sure you check the circuit board of the Io to insure the original (OEM Mills) resistors have been replaced with Roederstein. The Roederstein. are much quieter and better resolution. The defective Mills was the cause of all the uproar some years ago about "tube noise." It was defective resistors, NOT tube noise.

Jim White bought the most expensive, best quality, Military grade Mills resistors and they were bad. Caused him a lot of grief, I can only imagine what the US Government did to Mills over that deal.

As for different pin outs, I believe you have one older and one newer model power supply. The newer models have a SAFETY device. Remove the octal plug and the voltage is cut. Two places inside the Callisto and Io are 405 Volts and 610 Volts. The new plug is to protect users from being hurt.

VERY IMPORTANT !! If for any reason you wish to disconnect and re-connect the outboard power supply on Aesthetix Io or Callisto, you must wait 20 minutes before reattaching the umbilical cord.

The caps store energy and if you plug back to the main unit before the bleeder resistors bring the voltage down to safe level, you will blow the regulators. End result, no sound even though the tubes light up. Must be returned to the factory for repair unless you are very handy with a pencil solder gun and get instructions and parts from Jim White.
Very helpful post, Albert. Thank you! This has now gone into my permanent reference file on the Io.
A most valuable post indeed. Very much appreciated, Albert. I will try some of the recommended tubes to learn if they make as huge a difference in the Callisto as did so many tube changes in the Io. Fun Fun.
I'm looking to upgrade my linestage and the Callisto is high on my list because of what I've read on these forums (especially from Jafox). I'm not able to borrow one to demo it in my system but I was able to borrow an Io with dual PS, and volume controls (not signature). I'm running my digital front end through it right now.
How much difference is there between the perfomance of the line input on the Io vs. a Callisto signature?
Though I like what I'm hearing, I'd have to say that the sound (so far) is too dark and 'woolly'/fuzzy for my taste.
I'm comparing it to the EMM Labs DCC2, which I own, and the Hovland 100, which I borrowed.
Exlibris, there is a pretty significant difference between an Io Signature and the standard Io in that the Signature version delivers greater resolution, more neutral presentation and improved high frequency extension, among other things. Tube choices will certainly change the sonic signature as well. How this translates into what you may be hearing while listening only to the high level input of the standard Io with volume controls, I can't answer.

Albert Porter and others have noted that the addition of Callisto Signature as the linestage (compared to an Io Signature with volume controls) adds materially to overall dynamics and soundstage capabilities. I've not heard the comparison myself, but I trust Albert's comments.
Rushton, thank you. I don't think I'll get a chance to hear a Callisto signature in my system, however.
Just received an IO with volume controls with two power supplies, previously had VTL 7.5 MK 2 with Gryphon Legato Phone stage.

Source is Rockport Sirius 3 with Clearaudio Goldfinger.

The IO sounds beautiful and a considerable improvment, we only have one other source (CD) is the addition of the Callisto with 2 x power supplies really any better than this?

The IO sounds beautiful and a considerable improvement, we only have one other source (CD) is the addition of the Callisto with 2 x power supplies really any better than this?

Yes, In fact a Callisto with single power supply added to the Io will boost your performance. I have personally tested the Io with several preamps and the improved performance is directly related to the quality of the preamp added.

I must say the Audio Research Ref 2 with NOS tubes was a very good upgrade although not as grand as a Callisto. I have not heard the ARC Ref 3 in my system with an Io but would like to.

Congratulations on your upgrade, do you know what tubes are in your Io, original or premium NOS?
I did eventually have a Callisto Signature in my system for a few weeks. It is an incredible component. I'm using an Atma-Sphere MP-1 with my Atma-Sphere MA-2 amps right now. As expected there is great synergy between the two.
The MP-1 drives and controls (grips) my MBL 101Es better than any other preamp I've tried. I know it's odd to think of a preamp 'controlling' speakers but the difference between the MP-1 and other preamps in this regard (including the Blowtorch that I owned) is not subtle.
Exlibris, thanks for your follow-up comment about the Atma-Sphere MP-1 in combination with the Atma-Sphere MA-2 amps. I'm continuing to use my Aestheitx Io Signature with volume controls directly into my MA-2s (just as does Hemisferik). Albert's comments continue to tweak my curiosity about the improvement that might be possible with the addition of a high quality line stage like the MP-1 or Callisto, so perhaps this is something I'll have to explore one day.
I will check the valves and report when able to turn the thing off!

Currently loving it and pulling out all the old favourites (listening to Cowboy Junkies, The Trinity Session's)

IO without volume control's would sound best with Callisto?
IO without volume control's would sound best with Callisto?

No real performance difference between an Io with or without volume control.

However, buying with a volume control adds $2500 - $3000 to retail that could go towards the Callisto. Once the Io is joined up with a preamp (ANY preamp), the Io volume control is of no value.
Thank you Albert. Callisto on the wish list.

Moving into a new house/dedicated room soon. Chris Huston is doing the design.
Tubes are Electro Harmonix EL34 in the power supples. Sovtek's in the IO.

Can anyone recommend where to purchase the better sounding tubes Albert and others mention?
Albert I am trying to put together a list of ultimate tubes for the Aesthetix incl power supplies. I have read your recommendations but do you have a definitive list you could email me?

I am in Australia so it is not easy to source tubes here.

Thank you.
Hemisferik, here is the link to suggestions posted here at Audiogon.

Aesthetix tubes

No matter where you live the internet allows you to search world wide for tubes. The EL34 are easy, perhaps Mullard can be found locally. I've bought Telefunken tubes from a vendor in Australia, perhaps I can find his email address for you.

The best source for the ultra low noise tubes for the Io phono first stage is Andy Bauwman at Vintage tube here in the USA. You may email me through the Audiogon server and I will send you links to all my suppliers.
Wow, cool to see this thread still has a heartbeat. I started this thread for some assistance to get the Callisto "up and running". After reading much of Albert's tube advice, I started this thread to share my own tube experiences for the Callisto. So much had been discussed on the Io but not so much on the Callisto. Another thread to check out is here.

Last year I put a lot of time into investigating and trying out EL34 and 12ax7 tubes. This year I finally got around to trying many 6DJ8/6922 variations. The Tele 6DJ8 tube BY FAR is the most impressive of them all and it equally performs magic in the Io and Callisto whereas the Tele 12ax7 is wonderful in the Io but absolutely flat in the Callisto. For the Callisto I can't make up my mind if I prefer the Brimar or the Mullard gold pin 12ax7.

My Callisto is the Sig version but the Io is/was not. I took the Io over to Steve Huntley (GNSC) and he went through one pass on this, upgraded nearly half of the caps to Dynamicaps (the primary update for a Signature version), tweaked a few other things and added a bunch of dampening to the chassis. When we listened to this in his system a week or so later, frequency extremes opened up dramatically. Tonal coherency was far far better and thankfully that incredible bloom was there as before. Steve said he had some ideas to replace some parts in the PS and some more changes in the audio chassis. I would love to go for this but the sound is just so good right now that I am not ready to part with this for a couple weeks. But I will look to do this at the start of the year and report back. I feel very fortunate to be 15 minutes away from GNSC.

Why did you install NOS tubes and have your Io modified? Did you try to address a specific problem?

>>Why did you install NOS tubes?
After owning the ARC SP-10 and LS5/PH2 for a combined 15 years, I was familiar with the sonic differences between some brands of 6DJ8/6922 tubes. The Amperex were much more to my liking over the stock russian based tubes in the ARC models. However, I had little experience with the premium tubes from Mullard and Telefunken from decades ago. When I decided to try the Io (the non-signature model), I had read a lot of information on A'gon about how some tube changes could transform the Aesthetix models. The stock Io sounded pretty darn good but I wanted to hear what all the hoopla was about so I bought a dozen or so Mullard, RCA, Siemens and Tele tubes and tried them in the Io. All that I had read was instantly confirmed: $500-600 as a starting point to change out some of the Sovtek tubes brought on a huge refinement - the sharp edge of the Sovteks was gone and a more lush presentation was there. Since that time, I have pretty much finalized a tube set to my liking for the 2-chassis Io at just a shade over $1000 that takes this unit far far beyond what I ever could have imagined possible. Once you hear this, there is no going back to the Sovteks. And when I did a similar change to a CAT Ultimate II earlier this year, only then was that unit even listenable; the Sovteks there makes this preamp way too fatiguing to my taste.

>>Why did have your Io modified?
If you realize that the Io and Callisto are designs that are now 10+ years old, just all the improvements in passive parts alone has to imply a major benefit to upgrading the internal components. I investigated what the component changes were between the standard and signature Io. Considering the cost would be $2500 to "upgrade" to the signature version, and all the hassle, cost and risk of shipping these to/from the Aesthetix factory, I contacted Steve Huntley at GNSC to see if he would be willing to pop off the tops here and give me some insights and estimates as to what could be done. And I had a good idea as to the premium parts used in the signature since I have a Callisto Signature.

I heard my unmodified Io in Steve's system and compared to his phono setup, the Io had greater bloom and midrange definition, but clearly lacked refinement at the frequency extremes and also had mediocre resolution. Based on what Steve could hear that day, he was confident that a dozen or so select component changes would be a good starting point to tackle some of these weaknesses. And a week or so later, all it took was a quick listen to realize Steve's efforts had paid off. I could have left it there for yet another level of updates but it sounded so mighty good that I needed to get it home to enjoy the improvements. And because Steve is also here in the twin cities metro area, I could meet with him personally, talk about the pros and cons of each update and the respective cost and do a little at a time as there is no shipping back and forth. I am very fortunate in this regard to have this service locally.

As time goes on, I am more and more a fan of modifications once I find a product that really captures the essence that I seek. The Aesthetix models do this and becuase they have so much room in their chassis to take on the premium parts that are now readily available, it makes a lot of sense to do so. And when going down this route, the improvements you gain are at a cost that is impossible to achieve through buying a new model or a factory upgrade. Michael Elliot, the chief engineer of Counterpoint and Aria components, explains it best here.

For example, look at all the ARC line stages that have been their best model (LS5 I, II, Ref 1, Ref 2 I and II, and now Ref3) since the life of the Callisto. And imagine the cost it would have been to constantly upgrade from each to the next. The fact that the stock Callisto still competes after all this time indicates it was done right from the start. And if I can transform this design with $500-1000 in parts improvements to take it to the top of its class, then why would I want to "upgrade" to another model and take a multi-thousand $$ hit?
Assuming one were only listening to vinyl, in what sense is the Aesthetix Io with volume controls (or the Manley Steelhead with volume controls) *not* a full-function preamp?

Wouldn't adding a separate linestage just add more circuitry and another pair of interconnects to the signal path unnecessarily?

I don't doubt that both of these 'phonostages' actually sound better when used with a separate linestage, I'm just not sure why that is the case.
Exlibris says,
I don't doubt that both of these 'phonostages' actually sound better when used with a separate linestage, I'm just not sure why that is the case.

That sums it up, it just happens that the additional gain, impedance matching and circuity helps the sound.

Don't you think we Callisto owners would be eager to pocket the thousands of dollars from selling, plus freeing up shelf space if it did not matter a great deal?

The Io is great but it does not perform nearly as well by itself as through the Callisto (or an ARC Ref).

There are lots of things in high end audio that don't make sense, perhaps this is one of them.