Mr. Lin
Lunatic Member
Thus far I've had time for three reasonably long listening sessions, and the I+ has now spent around 40 hours hooked up to my Hagtech Frybaby for burn in, so I think it's safe to lay out some initial impressions.
I noticed right away that this amp simply sounds better than the modified Grado RA-1 headphone amp I've been using. That's saying a lot since the RA-1 costs about twice as much as the I+, which I purchased with the $50 WE408A tube upgrade (I know, I know, you can get those tubes cheaper, but hindsight is 20/20 etc...) at about $185 shipped.
I'm currently using the I+ exclusively with my fairly new Jolida 100 tube CD player. I did have some reservations about pairing up the two tube components, and whether that would be too much of a good thing, but in the end it's not really that much "tube" relatively speaking - meaning this is not an SET amp with a tube preamp and tube CD player, if you know what I'm saying. I did not expect the I+ to be neutral, considering it's low price, and that's pretty much the case, it definitely had the classic tube sound out of the box: three dimensional, warm, lots of tonal color. Fun, for sure, but far from mind-blowing, which I did not expect either.
I took the fact that the sound of the I+ didn't knock me out of my chair in stride because it's a versatile little amp, and I've already built up a small army of things to try with it. For those who don't know, the I+ is a hybrid amp, using both tubes and transistors. Now, I would have gone with one of the other all-tube models but for one thing - well two things - the low price, and, more importantly, the option to "op-amp roll."
In fact, the I+ was designed with obsessive compulsive people like me in mind. There's a single dual circuit op-amp that's installed in a DIP gold plated socket, allowing easy removal and installation of different op-amps, and durability since you know most of us are not going to leave well enough alone and just try one or two different op-amps. 
I'll talk a little about how the op-amp thing is going so far because I've tried three, including the stock one. As of yet I have not tried any other tubes, though I have two extra pairs and another in the mail (thanks Jim!). Right away I can tell you that the stock op-amp is not impressive. I've been going through the massive tube and op-amp rolling thread on Headfi and noticed someone's comment that the stock op-amp was sort of a bottleneck, restricting performance, and I think that's a good way to put it.
Last night I tried the BB (Burr-Brown) 2134PA in the middle of a listening session. The difference was very small, a slight increase in detail, just a little better than the stock op-amp, but noticeable. Tonight I switched that out for the BB 2107. This made a very big difference, actually more than I'd anticipated changing op-amps would yield. Even more detail, better imaging, and a more dynamic sound. Listening to XTC's "English Settlement" before and after, the 2107 made everything more punchy, with great impact, and not just percussion instruments. The sound of guitar strings being plucked is much clearer. There's more micro-detail, making instruments and voices sound simply more realistic. In short, there's more life to the music now. Very nice, I feel like I'm starting to hear more of what this amp can do.
I'll end it here for the moment until I've had more time to listen. Eventually I plan to start a separate thread focusing on what I hear (or don't hear) with specific op-amp models, and I hope others will chime in with their experiences. I plan to try a pair of NOS Telefunken CV4010 tubes tomorrow, I'll update at that point.
Thanks to everyone who contributed to my other thread asking about the I+, which made it a little easier to decide to buy it.
I noticed right away that this amp simply sounds better than the modified Grado RA-1 headphone amp I've been using. That's saying a lot since the RA-1 costs about twice as much as the I+, which I purchased with the $50 WE408A tube upgrade (I know, I know, you can get those tubes cheaper, but hindsight is 20/20 etc...) at about $185 shipped.
I'm currently using the I+ exclusively with my fairly new Jolida 100 tube CD player. I did have some reservations about pairing up the two tube components, and whether that would be too much of a good thing, but in the end it's not really that much "tube" relatively speaking - meaning this is not an SET amp with a tube preamp and tube CD player, if you know what I'm saying. I did not expect the I+ to be neutral, considering it's low price, and that's pretty much the case, it definitely had the classic tube sound out of the box: three dimensional, warm, lots of tonal color. Fun, for sure, but far from mind-blowing, which I did not expect either.
I took the fact that the sound of the I+ didn't knock me out of my chair in stride because it's a versatile little amp, and I've already built up a small army of things to try with it. For those who don't know, the I+ is a hybrid amp, using both tubes and transistors. Now, I would have gone with one of the other all-tube models but for one thing - well two things - the low price, and, more importantly, the option to "op-amp roll."
In fact, the I+ was designed with obsessive compulsive people like me in mind. There's a single dual circuit op-amp that's installed in a DIP gold plated socket, allowing easy removal and installation of different op-amps, and durability since you know most of us are not going to leave well enough alone and just try one or two different op-amps. I'll talk a little about how the op-amp thing is going so far because I've tried three, including the stock one. As of yet I have not tried any other tubes, though I have two extra pairs and another in the mail (thanks Jim!). Right away I can tell you that the stock op-amp is not impressive. I've been going through the massive tube and op-amp rolling thread on Headfi and noticed someone's comment that the stock op-amp was sort of a bottleneck, restricting performance, and I think that's a good way to put it.
Last night I tried the BB (Burr-Brown) 2134PA in the middle of a listening session. The difference was very small, a slight increase in detail, just a little better than the stock op-amp, but noticeable. Tonight I switched that out for the BB 2107. This made a very big difference, actually more than I'd anticipated changing op-amps would yield. Even more detail, better imaging, and a more dynamic sound. Listening to XTC's "English Settlement" before and after, the 2107 made everything more punchy, with great impact, and not just percussion instruments. The sound of guitar strings being plucked is much clearer. There's more micro-detail, making instruments and voices sound simply more realistic. In short, there's more life to the music now. Very nice, I feel like I'm starting to hear more of what this amp can do.
I'll end it here for the moment until I've had more time to listen. Eventually I plan to start a separate thread focusing on what I hear (or don't hear) with specific op-amp models, and I hope others will chime in with their experiences. I plan to try a pair of NOS Telefunken CV4010 tubes tomorrow, I'll update at that point.
Thanks to everyone who contributed to my other thread asking about the I+, which made it a little easier to decide to buy it.
ara: