They can both sound good, but when direct comparisons are done, the inner detail and vocal smoothness are usually superior on the upsampler due to the very high frequency filtering and the interpolation (if the implementation is done right). The Audionotes use the natural roll-off of the transformers (low-order) to achieve a more natural sound, which works well, but this also limits their high-frequency extension. Harpsichord, for instance, sounds very natural on an upsampler, but not as natural on the Audionote.
Its a matter of taste. The upsamplers can cause a bit of unnaturaleness (maybe not as smooth), but the non-upsamplers have other shortcomings.
Its a matter of taste. The upsamplers can cause a bit of unnaturaleness (maybe not as smooth), but the non-upsamplers have other shortcomings.