Yesterday afternoon I spent several hours at LTA HQ demoing the Z10e and the Aero DAC. I also brought along my Ferrum Erco Gen 2 for comparison. The Z10e's independent, per-input volume control was very useful for volume-matched comparisons between them.
For reference, the Erco Gen 2 acquired a number of technologies that were originally developed for the Ferrum Wandla DAC such as an improved discrete I/V converter as well as an improved apodizing digital oversampling filter developed in conjunction with the creator of HQPlayer. So the comparison is between an ESS9028Pro-based DAC with a solid-state output stage plus mini-HQPlayer built-in and a non-oversampling R2R DAC with a tube output stage. I listened with the stock tubes, which are 12SN7s with the GE label on them.
I had the preconception going into the demo that the Aero would be "tube-like", warmer, softer, thicker, bassier, maybe a bit smoothed over or rolled off in the treble with a bit less detail. All of the adjectives that people like to use for tube gear. Well, the Aero didn't fit that mold. I could not hear any lack of detail vs the Erco, which is impressive. I thought that the Erco Gen 2 with its improved upsampling filter was a notable improvement in detail perception from the Gen 1 Erco, and the Gen 2's improvements were similar to what I heard when using HQPlayer on my PC audio setup. And the Aero matches it in detail without any oversampling, with tubes in the output stage, and with a legacy 18-bit R2R chip as its DAC.
I'll go into more detail on its sound in a future post, but I got an interesting tidbit from conversation with LTA's Nicholas about the input board on the Aero. As noted earlier in this thread based on pictures of the internals, the Aero uses an input board from HEM, which is the parent company of Ferrum Audio. I asked if it was possible to port the Wandla's digital filters to the Aero given the use of the board, but the Aero only uses the input controller board while the digital filters are implemented on a different board on the Wandla, so the hardware isn't available to use oversampling filters. Nicholas also said that it was nice to work with HEM, which I like to hear.
