Has anyone perhaps compared this UD-501 to the UD-301? Used purely as a DAC, other than the filters and 384khz capability, are there any differences (functionally or sonically)?
Teac Reference Line UD-501 USB DAC "DSD" - Page 22
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The major difference is in headphone amp section, UD501 seems to have dual op-amp units for each channel, while UD301 seems to have only single op-amp unit for each channel.
No, UD501 only has one dual op-amp per channel in the head amp. This stage immediately follows the analogue stage after the dac and is in fact one of the three output options that follow ie RCA, XLR and the head amp. This means the quality of the head amp is affected by the I/V filter op amps and output caps and then it's own op amps and output caps.
The UD301 has capacitor-less output head amp so one less thing to worry about. It also seems from the teac website the UD301 head amp has an additional op amp stage making it two op amp ics per channel. Could be the buffer for cap less output?
The website also says only two muses op amps are used whereas in the 501 four are used, two per channel for the I/V. Voltage rails are + and -12V with each channel powered by a separate transformer. The 301 only has one transformer so maybe the voltage swing is less, and only one Muses used?
I changed out all the op amps in my 501 as well as the output caps, voltage regs and power caps. The head amp can drive T1's to deafening levels at less than half way up the volume knob with its op amps changed to dexas.
Edited by 37mil - 1/30/15 at 9:43am
I just looked up some 301 internal pics on the net and saw it does have 3 dual op amps per channel. Oddly, it seems the muses are placed at the I/V stage mixed with one 5532 followed by another 5532 filter output.
The 501 had two muses for the I/V followed by the 5532 per channel.
Maybe an expert can clarify?