1. Are you familiar with SACD? DSD?
Yes
2. Do you own any SACDs?
Yes
3. If so, what percentage of your collection is SACD vs CD or files?
Maybe 10% SACD, 5% downloaded (lossy), 85% Ripped CDs. Most of the SACD's are hybrids and I'm in the process of ripping the Redbook side.
4. Is SACD/DSD decoding an important consideration when you're looking for a DAC?
It used to be, but Sony's predictably complete blundering of the format has made it much less so. Very little music I seek is, or ever will be, available on SACD, or hi-res download. Telarc was the last holdout for SACD for me, but even they've pretty much scrapped new prints. DSD is a very good format, and I'd like to see it become available in downloadable content. If it does, I will return to it. But physical SACD discs seem all but out of print today. Worse, disc players that can play them almost universally have no digital out save for a handful of newer HDMI 1.4a players, so none of my players could utilize the feature on an outboard DAC anyway.
5. If you owned a DAC that could be upgraded to playing SACD/DSD, what would you pay for the upgrade?
In the present market for SACDs and HDMI 1.4a players that could export digital DSD, $0. If DSD picks up stream and becomes a viable digital format with a useful library of media, up to $100, same as USB on Bifrost.
If the question relates to possible features on the statement DAC, which will be released within the next year, there's too little SACD market to warrant $100 on it, yet it would hardly be a statement DAC without the option.