Aesthetix IO Modifications

I read the recent Audio Critique posting on the Aesthetix IO phono preamplifier recently in which the site conferred a "Class A, Lower" ranking on the product so long as it was modified. It had been kind of a long dry spell for the product on that site so far as I was concerned; I believe the Io has been in production for more than ten years and is almost universally praised. I have owned an Io for about 1.5 years and thought it was a great phono preamp.

Having a high opinion of the product, however, is a passing fancy for any audiophile and I tried to find a way to increase my already substantial satisfaction.

I started at a pretty high level: My IO was a Signature version with two power supplies and volume controls. This was not an Eclipse version, though I considered sending mine back to Aesthetix for their upgrade to the Eclipse level. I decided instead to consult with Steve Huntley at Great Northern Sound Company. We spoke about my system and priorities for the sonic characteristics we wanted to achieve with mods. I felt that Steve knew what I was looking for and that he had some solid ideas for achieving those goals.

I received the IO last night and understand that it has not fully run in but the sound far exceeded my expectations at this stage. The lower registers were full and voices had a solidity and body that I have only heard when using the Io. I highly prize sound that rolls up from the lower midrange and avoids upper midrange and lower treble emphasis. Live music never sounds bright to me in the ways that audio components often do and the modified Io avoids the errors of most other phono preamps I have heard and betters all others I have heard overall. No other phono set up has come through for me in that way of presenting solid, believable vocals and instruments. While I believe that there will be additional progress as the Io further runs in, particularly with respect to openness and extension on top, I have no dissatisfaction with the result as is. The Io substantially exceeds my recollection of the unit before modification.

A benefit (to me) of this modification is that I played some small role in creating a product very much tailored to my requirements. Steve and Scott Rolfes at GNSC really lavished attention on the Io, chocking it full of Black Gate caps and V-Caps, replacing some original EL-34's derided as "nasty" and applying damping that was obvious even as I activated the power switches. Their obvious pride in the unit only amplified (sorry) my own.

Anyway, I wanted to agree with Audio Critique's tardy recommendation and encourage other Io owners to stick with their Io's and find ways to improve what is already a fantastic product.
Is the mod to the IO also applicable to the IO SIGNATURE? I would be interested in to what the mod to the Signature is compared to the next level from Aesthetix for the IO series. How much did the mod cost and how long was the turn-around time? What is the contact information for the dealer? Thanks,
My Io started as a Signature version with two power supply chassis and volume controls. I have not heard the Eclipse mod, which uses "stealth capacitors." Where the stealth caps are in the Eclipse mod from Aesthetix, mine has V-Caps. The power supplies in mine are chock full of Black Gates.

Since I have not directly compared the Eclipse and GNSC modified versions, I cannot give you details of an A/B.

Turn around times for mods from Great Northern Sound vary according to the then current level of modification activity. This one was a lot of work and took a couple of months. The total cost of the mod was $5,000, but my mod cost more than others may because of the two power supply chassis on mine. If you have a single power supply chassis, or you have different requirements, your mod costs will likely vary.

Great Northern Sound Company is in Stillwater, Minnesota and has a website at with all of their contact information if you want to go and check them out on the web.