Good morning. I received the Si-1 and connected it last Thursday. My first impression was that it sounded rather dull and closed in, particularly on such music as acoustic guitar and even vocals. Bass had impact but seemed to have lost some of the lowest frequencies. Hmmm, this was all a surprise. I thought that maybe it needed some run-in time. To be sure I didn't miss any potential of properly running it in, I played a V-tuner station of rain/thunder so there was sure to be signal passing through the device and let it run overnight. The next day things sounded much better but still not quite to my expectation. One more full day of running the V-tuner and by Saturday everything was what I had anticipated it to be. I didn't expect an item like this needed much run-in time, but for me and in my system it did. My system is highly resolving but definitely not bright, and I do NOT prefer a bright sound quality. As a reference to my sound preference, and to understand my system, it consists of the latest generation of Balanced Audio Technology (BAT) components; preamp, phono stage, and monoblock tube amps. Speakers are Daedalus Audio, model Apollo 11 (soft dome tweeters). Turntable is Feickert Analogue, model Blackbird with Kuzma Four-Point 11" and several phono cartridges (Lyra, Soundsmith, Hana, and soon adding Phasemation SUT and cartridge). Audioquest full loom of top tier power cords, signal and speaker cables. Symposium Acoustics equipment racks, amp stands, and roller blocks. Sound room is fully treated. That should give you an idea of my musical sound preferences. So, when I say my first impression of the Si-1 is that it was dull, please take my system into consideration.
Back to how the Si-1 became what I had anticipated it to be. The previous connectivity was simply having the Stack Audio Smoothlan, placed just before the streamer. In that setup music generally sounded quite good, but no doubt there were plenty of times that it seemed to have a "digital edginess" to it. Especially on guitar strings of the higher registers, both acoustic and electric, and also with horns such as trumpet and alto saxophone. Of course, better recordings sound superior to lesser recording qualities, but still, analog for this music has been my preference and reference. Now, however, the Si-1 is providing a much smoother presentation than what I had before, and with a complete audio frequency spectrum. Fluid, organic, natural and simply put, very comfortable for listening to the music. All of the details are there, nothing is missing or subdued, everything on the soundstage unfolds and presents from a very black background, and everything sounds as it should, i.e., like music. That "digital edginess" is gone from those same songs and musical passages where it once was, and the music sounds wonderful. Additionally, I have found that bass lines are more discernable than before. I can follow the bass line with ease, and those very low frequencies are exactly where and how they should be. Another virtue I found is that the soundstage got a little wider. I always had a great soundstage, width & height & depth. So, to achieve a little more width is very welcome. Imaging is also a bit more believable. That is, the air around the instruments and vocalists provides more separation and spatial locality with excellent depth of field on the soundstage.
I am gleeful to report this device is an absolute winner, and especially at just $699. I was at first a bit dismayed, but again, in my system and for me that was the case. After about 50 hours of run-in time, it has settled in as a delightful addition to my system. And as others have stated, here in this thread as well as in other reviews, it is not a night & day system upgrade. It's not like changing from a $299 phono stage to one that is north of $10K. However, it is a real component in the digital audio chain that, given a high-quality system, will provide sonic presentation benefits that are indeed satisfying and bring an overall more comfortable, balanced, and enjoyable listening experience. Maybe this device should have been named the "Smoothlan" because, indeed, that is what it provides.
I don't see a need now to also add in an expensive switch. As Lalitk stated above, it would be redundant. If there are other opinions on that, I welcome them.
Thank you for taking the time to read all of this. I hope my evaluation helps, for those who are interested in the Si-1.