Guru (gsferrari) and I got together at my home today (i.e., Wednesday), and we did some comparisons of the SI Portable T-Amp. (which cost me $21.12, and which I powered with a Radio Shack 13.8 volt, 3 amp. power supply which cost about $38), to my ASL AQ-1005DT 300B tube amp. (that cost in excess of $1,000). Thus, the comparison was between the Portable T-Amp, and the ASL AQ-1005DT amp. In addition, the powered output of a SinglePower SDS amp. was used as preamp. for driving the AQ-1005DT power amp. We had only enough time to use only a single recording for our tests; i.e., the DVD-Audio version of "Buena Vista Social Club." These listening tests were, of course, done with a K1000. Well, the results were truly amazing. With Guru turned around (i.e., facing away) I switched (i.e., alternated) connectors between the Portable T-Amp., and the AQ-1005DT amp. After switching between these amps again and again (i.e., each time that Guru signaled for a change), he announced which amp. he considered best. As amazing as it may seem, Guru's decision was that the Portable T-Amp. sounded best. We then repeated this test by having me turn around, and Guru switching (i.e., alternating between the amps.). As amazing as it may seem, I came to the same conclusion; i.e., I also selected the small, $21 amp. as the one that produced the best sound. Since it's still hard for me to believe, or accept, these test results, I'll repeat these tests with additional types of music; i.e., additional to the single recording that we used for these tests. Perhaps, the results will be different when listening to complex classical orchestral music. If I find that the preceding conclusions change, I'll certainly report such results.
I also tried to connect an ASL UHC-Signature headphone conversion device to the Portable T-Amp. Use of this device makes it possible for regular headphones to be driven by regular speaker amps. For example, I routinely drove an RS-1 and an R10 using the large AQ-1005DT amp., by connecting the UHC-Signature device to the AQ-1005DT. The RS-1 and R10 headphones were then plugged into the UHC device, and they played beautifully. Well, connecting this device to the Portable T-Amp. did not work out. The result was that the T-Amp. clipped badly, and was thus not able to be used to drive the RS-1 or the R10. When I described this problem to Guru, he said that a simple modification that he could probably make to the T-Amp. may make it usable for driving these regular headphones. Well, since I purchased two of these Portable T-Amps., I gifted one to Guru. This gift was for the purpose of giving Guru an opportunity to try to modify this amp. so that it could be used to drive regular headphones. BTW, Guru's thread describing our meeting is available at:http://www6.head-fi.org/forums/showthread.php?t=95632