Ok, here goes. Shipped the iTube2 off to Tommy2Tones this morning. So, it's time for my review. As reminder, here's my system:
microRendu > Lampizator Big7 w/volume control (R2R, but no superclocks - Takatsuki 300B's and Lampi Anni 5URG recti) > Line Magnetic 518ia (Psvane WE845 replicas, 1957 metal base 5AR4) used as straight amp bypassing its volume pot > Daedalus DA-RMa V2 speakers
Dual 15" subs driven by amp level inputs - placement and settings from REW/microphone trial and error
Entire digital source side including network switches/routers driven by either Uptone LPS-1's or HDPlex linear power supply with iFi DC iPurifiers.
Lampi and Line Magnetic power from a Zenwave SurgeX power conditioner with Furutech NCF outlets, and wall outlet is Furutech NCF as well - and all power cords are Zenwave PL11's with Furutech FI50 connectors
IC's used were Zenwave D4's, and speaker cables are Cable Research Labs Bronze
Music was mainly streaming from Tidal (though not with MQA engaged)
Basically, I've done everything I can to feed the Lampi and Line Magnetic with the cleanest low noise power and source signal I can, and each one of the cabling, power conditioning, and especially power supply upgrades to the network gear have upped the inner resolution, refinement, and also warmth/body of this system.
So, the iFi iTube2 went in between the Lampi and the Line Magnetic. Lampi has an excellent integrated passive attenuator, and there are so many options with the iTube2, that I focused my listening on the buffer settings and not on use as a preamp - I just continued to use the Lampi volume control.
My first impressions were with the buffer setting at 0dB gain. I listened to this for an evening, and honestly I felt there were positives and negatives to the sound. The system without iTube2 had more warmth and organic engagement, and in some senses it had more overall musical information. Yet, with the iTube2 in the system, the sounds of vocals were clearer and cleaner, and there also appeared to be greater soundstage depth and PRAT. It was hard to decide which sound I liked better.
My second impressions were with the buffer at the 9dB gain setting. I listened to this setup for several sessions of 1.5-2 hours. This was a different story. Without swapping back and forth, it was a very engaging sound. I would mainly listen for a while with the iTube2 in the system, and then toward the end of the listening session, I would remove the iTube2 after listening to a well-known song or passage, and then replay that song/passage without the iTube2, and then re-insert the iTube2 and listen to the same song/passage again. I might do this 3-4 times with different songs/passages in the last 30-40 minutes of a listening session.
Basically, I found the iTube2 to have a cleaner and also more relaxed sound, with a slightly less dense portrayal of instrumental body/warmth, but with overall better clarity and finesse. I thought my system was already very clean and refined and resolving. But I'll be damned if the iTube2 as a buffer with gain didn't increase overall refinement. Voices lost a bit of stridency, sibilance was reduced, reverb and ambience had even more extended decay and detail, complex passages had even more instrumental separation and placement - just all around more resolved and refined sound.
I did prefer the iTube2 with the SET setting more than the standard or Push/Pull setting for the tube in this system. And it was a tremendous help to have these options to play with to find the right fit for the system.
So, I've placed my order for my own iTube2. And it has convinced me that a preamp is definitely needed in my system. Maybe the iTube2 will retain its place of privilege in the main rig, but I'll also be interested in checking out some 6sn7 based preamps like the Don Sachs or the Linear Tube Audio stuff based on Dave Berning's work to compare with it. If any of them are a better fit in the system than the iTube2, I can always make use of it in my TV system.
Which brings me to the TV system. I also tried the iTube2 for a night in that system - which is just a simple Schiit Modi2 DAC, older Acurus preamp, and Miniwatt S1 amp, powering Tekton Lores that have rebuild crossovers with upgrade caps/resistors and wiring. I didn't do any careful comparisons in this system, but the iTube2 was a cleaner and clearer preamp than the Acurus.
So, that's my review! Hope it's informative for some of you. And in the end, I concur with Tyson that the iTube2 is no joke, and can easily find a place in a very high performing system, despite its relatively modest cost. And I do wonder what it would sound like if powered by a 12V Vinnie Rossi outboard supercapacitor power supply...which is what I may try if one of these 6sn7 preamps doesn't unseat it.
