[dredgmo]

I'm currently using the ATH-M50s cans as well as the FiiO E7 Amp/DAC through an older set of Logitec 5.1's.  I'm happy with the sound overall, but I have a few questions.
 
I get quite a bit of hum through the FiiO at loud volumes.  The FiiO runs through an external Logitec volume controller.  Looks similar to this:
 

 
I can start hearing the his/hum around the 50% volume mark on the FiiO w/ the volume on the Logitec around 4/10.  I've eliminated the FiiO altogether and hooked straight into the Logitec unit and have eliminated all hum, but lose a bit of quality and have to crank the volume to 7/10 to get it to "loud" which is where I most enjoy my music.  So I can only assume my problem is with the FiiO.
 
I tend to listen to metal, but it varies.  I want a heavy, fat sound, to enjoy my death metal, but something versatile enough to indulge in my lighter side.  (Think Black Dahlia Murder/Opeth one minute to Radiohead/Neil Young the next).  I've been eyeballing the:
 

MP-301 MK2 Mini Tube Amplifier

http://www.musicalparadise.ca/mp/index.php?main_page=product_info&products_id=75
 
This is in my budget currently.  Whatever I end up with, I can see myself having it for years as I really can't invest a lot of money into this like I would really like to.  Are tube amps something I should be looking for?
 
Thanks so much in advance.  I've really enjoyed everything I've learned from here in such a short period of time.

 

[FortuneSound]

Have you try to use the E7 without the Logitec volume controller and use a usb cable to connect it to your pc instead of the 3.5 mm input jack? If you use the 3.5 mm input jack, you are not using the DAC feature and you amplify the noise of your soundcard along with the music.

 

[dredgmo]

I have not.  I'll give that a try!  Thanks so much.