[ADD]

I'm currently looking at getting a tube based headphone amplifier to plug in between my portable player and my Westone UM2 monitors. Shortlist candidates at present are something from either Eddie Current (Lunchbox II) or Little Dot. I think Eddie Current might have the nod though.

Since I am not at the stage of purchasing yet, I currently have in my possession an AudioDigit Tubalizer. For those who don't know, it's a tube-based line level output buffer. I wanted to try this just to get a basic idea of what tubes might do and whether the sound signature suits my listening.

On the positive side, I am happy to report that this tubalizer has a wonderful sound signature and it's exactly what I was hoping for when listening to my classical music. On the downside, this thing simply refuses to work with my portable player connected to it's line level inputs, but it works absolutely perfectly if I connect it to the line out jack of my computer sound card or the line out jacks of my DVD player.

If I connect my portable player (IRiver T60) to the RCA input jacks (using a mini to 2 x RCA cable), the sound is extremely soft, extremely anaemic and severely distorted. This suggests to me that the sensitivity and impedance of the RCA line input is a terrible match for the headphone out of the IRiver portable player. My guess is that the portable player simply cannot produce enough voltage when connected to a line input as opposed to having headphones connected to it.

This now has me worried that any headphone amplifier I consider could present with the same symptoms - that is, no problem when connected to something like a CD /DVD player or computer soundcard line out, but hopeless if driven directly from a portable.

I'm not really sure if there is a foolproof way of determining upfront if there is going to be a mismatch like this or not. I really want tube sound, but alot of the source music I am now buying is directly off the internet, encoded as 320 kbps mp3 files. It's not something I really wish to have to buy a full sized player for when the portable works fine as it is - especially as a huge advantage of a portable, tiny monitors and something like a Lunchbox is the small amount of desk space it takes up.

Can anyone shed any sensible light on this subject?

 

[Frihed89]

Many of these output stage thingees add warmth + noise + distortion - detail. If you are using a portable digital source, my guess is that the signal is already pretty noisy, distorted and compressed (for lack of a better term). Add a tube buffer and you may get a truely awful result.

Here's my biased 2 cents.

1. Don't try to fancy-up a portable player-source (unless there's something I don't k now about). It's not worth it.
2. if you want to do serious headphone listening to compete with (or compliment) speaker use buy a decent CDP and a real amp.

 

[ADD]

Nothing you have said addresses the specifics of my question. The sound out of the player is extremely good and clean. I simply wish to add a tube signature to the sound because tubes are the only things on the planet that can reproduce orchestral string sounds properly. And they can do this whether the source is a 320 kbps mp3 or a 96000 Khz, 24 bit master tape. I can plug my portable player into my computer line in and then connect the computer line out to the tube buffer, the tube buffer to a cheap $20 headphone amplifier and the cheap $20 amplifier to the headphones. Even in that situation the resultant sound is clean with absolutely no "breakup", excellent volume and the strings sound much better than they do straight out of the MP3 player.

This issue has very little to do with the potential audio fidelity of the source but it has everything to do with being able to match the output of the source to the input of the amplification correctly. That is what I am trying to find then - what tube amplifiers will work with a portable player connected.