Alan, I have heard several times that the Infinity fuse provides same performance but has the adjustable amp levels for convenience and flexibility. I prefer the size and case of the SDFB but the dip switches are a really nice feature.  If I was to buy again I would get the Infinity.  I do change gear a bit and have had to get one of my SDFB sent in to reprogram which is a bit of a hassle.

AC Tuning X in house and worth the wait. Yet another great product from Vera-fi Audio.  Even right out of the box I heard a nice overall improvement and one less cable is a bonus.  On my system the improvements that I heard were:  Overall sound and tone quality improved, sounded less congested, clarity and air increased, instrument separation enhanced, more 3D and holographic, bass more tight and defined and overall just had a bit more gain. These improvements were not major but definitely noticeable.  When I removed the ACTX and went back to my cable sounded a bit dull, veiled, soft and just not as dynamic or engaging.  Kind of reminds me of the 70-80’s when you pushed the “Loudness” button🤣.  The ACTX is a winner with me.