How much better does the Signature sound?
TL; DR. Pro iCAN a good +10% but the Pro iDSD is a really nice +20%.
You asked us – so we asked our Lead Tech: Colin F to fire up the Stax 009s+iESL and play some of his most demanding tracks and to report his findings.
Here’s what Colin said:
"The original Pro series is already sonically superb, with its unique sense of drive and rhythm. It’s musical, especially set to ‘Tube’ position, my favourite. The Signature version adds even better audiophile parts in critical areas and revises the input section of the amplifier section. Think of having an F1 race car but once developed (Original), you then take it round Silverstone to refine it painstakingly further to the max (Signature).
The Pro iCAN Signature sounds a touch more resolved, especially noticeable in the midrange, and it has a slightly inkier dark background. Overall, a worthwhile improvement that draws you in before you know it!
The star of the show for me though, is the Pro iDSD Signature.
The team worked hard to lower the noise on the regulator circuits in the digital engine and on the analogue power supply. That translates into even lower jitter.
The output stage has received some revision for its operating parameters, and there are even better parts than the original.
When I first put it on it was love at first listen, the depth hits you! Transparent and musical, it’s masterful at letting you hear exactly what is in a recording without sounding like its thrusting detail at you, a nifty but difficult trick to attain. Not that the original Pro iDSD is any slouch, just that the Signature sounds like it’s taken the original design and optimised everything. Which indeed is what’s been done!"
Music Notes
Walking on the Moon (Police) - this track has some great hi-hats and cymbals, also the reverb added in the left channel tells quite a bit about how natural it’s sounding. At 3:12, the snare drum should ‘crack’ with a single-double hit, instant thwack on the Stax! You should be able to hear the skin of the snare. The hi-hats afterwards have their own distinguishable sound character, easily lost on lesser systems. The reverb in the left channel should sound like natural room ambience, not like it’s a swooshing hiss. The Pro iDSD Sig lets you hear it easily and suspended in limitless depth.
Can’t Stand Losing You (Police) - shouldn’t sound metallic or flat. Proper depth lets you hear the ambience through all the compression and rolled-off top end. The voice is very forward, lesser systems put Sting about level with the drum kit.
Blow Out (RadioHead) - distortion easily heard on multiple dubs at around 0:24. Cymbals shimmer at 1:21, they have that intense sheen easily glossed over on a 2D system, it can end up sounding like noise instead of shimmer. After 3:40 the guitar solo begins to intensify. Be careful the soundstage doesn’t collapse into a smear of distortion; it should remain clear and supporting instruments easily heard in their own separate recording chambers
How I Made My Millions (RadioHead) - lots of stuff happening in the background, moving items, snare drum resonating, zip tinkling against the piano, piano stool creaking. Colin Greenwood is rocking on the stool. The piano itself should have clear harmonics - the Pro iDSD Sig conveys that well, it’s quite comparable to real life.
Mahler Symphony No.2, Minnesota Orchestra, BIS The orchestra tone shouldn’t be cold or steely. The hall ambience and its dimension should be easy to attain with no extra HF noise. There is lots of depth on this recording, and a system with proper depth resolution will let you hear it.
Bartók, String Quartet No.2, 2nd movt. Takács String Quartet, Decca. One of my references for string tone. The string positions shouldn’t be flat, they have a modicum of real space and air that’s mostly missed on solid state systems. The four players are arranged in a semicircle, and you can hear their feet tapping the wooden stage floor. The chamber ambience shouldn’t be dry, and you can hear it swirl around the players. The 1st violin tone is intensely full of harmonics. All this is virtually inaudible on lesser systems.
