DACs and bass response?

Why would someone buy a tube component that almost sound identical to Solid State?

Because Tubes are usually lacking in dynamics, bass tightness or HF extension. You can get the liquid midrange of tubes and the dynamics, bass and HF extension of the very best SS without having that "tubey" distorted sound.

Steve N.

Empirical Audio

The J-test uses a known digital signal and analyzes the spectrum of the analog final output of the DAC for spurious frequencies that should not be there. It is actually a complete approach to testing the entire audio chain from digital signal passed through any cable into the digital input of the DAC and a detailed examination of the final analog output. Any jitter at all anywhere that reaches the D to A chip will result in quite obvious spurious analog signals that do not match the known input. Any source jitter, cable jitter, interface jitter, LIM jitter and intrinsic jitter (in fact the sum of all and any jitter) is tested for.

I don't believe the DAC output is a good indicator.  It will change with every DAC you use in the test, so testing for instance a reclocker or a USB or Ethernet interface would be insufficient.  What if the particular DAC used introduces spurious signals unrelated to the jitter of the incoming signal?  It is a result of the DAC, not the USB converter driving the DAC for instance. I also don't like using a fixed signal.  I would rather see actual music data.

I have seen lots of J-test plots in Stereophile over the years.  None of them seem to correlate well with sound quality.  I think this direct digital measurement I am making is superior to the analog measurement for correlating to SQ. So far, its helping me make decisions on future products.

Steve N.

Empirical Audio