After getting all the components I needed I was finally able to directly compare my Sabaj A30a with my Rotel RSX 1067 7.1 AV receiver (
https://hometheaterhifi.com/volume_12_1/rotel-rsx-1067-receiver-1-2005.html). The RSX 1067 was a gift from my family for my last birthday (it belonged to a friend). It was launched by Rotel in 2004 (at €3000), it’s build like a tank (it has a huge toroidal transformer) and is a beast of 24,6 kg, 2x120 W on 8 Ohm and up to 990 W of power consumption (130 w idle power consumption, 19 w when in standby!!!). I had to bring it in twice for assistance for a problem of the DSP with one of the two front channels and it was an experience that my back will remember for a very long time.
The setup for the test is depicted in the image below and includes two "magic box":
- a two port Toslink SPDIF Splitter (that is also a Toslink to Coaxial converter and viceversa). This little jewel costs around $15 (
https://www.amazon.com/LiNKFOR-Bi-Directional-Converter-Splitter-SoundBar/dp/B08DXTJLQH) and is able to support up to 192 KHz sample rate as displayed by both the DAC and the Sabaj A30a.
- a amp switcher/speaker switcher (
https://www.amazon.co.uk/dp/B093LNGJR3). It’s a little bit expensive but is well made and the ground is not shared between the two devices, something that seems relevant when one of them is class D amplifier.
The test was carried out using as a source a Wiim Mini playing mainly jazz music from Tidal (44.1 khz 16 bit). I used matching volume on the two amps (mostly medium volume) with the tone controls set to zero (flat). On the Rotel RSX 1067 I tested both the “stereo” (DSP active) and “bypass” (DSP off) modes.
For the test I used my Dali Zensor 3 bookshelf speakers (I had no time to switch them with my Elac Vela BS 403). I know the Dali are not considered “audiophile grade” however they perform pretty well in my room and are quite analytic on the mids and highs.
All this to say that… I could ear no difference when switching from A to B the commuter on the SOLUPEAK P2 box. At first I was so surprised that the two amps sounded identical that I had to switch one of them off to make sure I didn't make any mistakes with the cable connections. Perhaps (I repeat, PERHAPS) the Sabaj is a little more "airy" in the medium frequencies but I wouldn't be willing to bet more than one Euro on this. Only at higher volumes I was able to hear a fuller sound (= with a bit of emphasis on the bass) from the Rotel with the DSP active (Stereo mode).
I do not know how to feel about that...
Based on the Amir's reviews of similar amps, the Rotel RB-1070 power amplifier. (
https://www.audiosciencereview.com/forum/index.php?threads/rotel-rb-1070-amplifier-review.41193/ ) and SMSL VMV A2 full-digital amplifier (
https://www.audiosciencereview.com/...msl-vmv-a2-review-stereo-amplifier-dac.24640/), my guess is that there is a SINAD difference of ABOUT 15 db (~80 db vs 95 db) to the advantage of the Sabaj.
Two additional considerations: 1) I’m in my early sixties and my earring is not that selective anymore; 2) no comparisons have been made playing music loud.
That's all folks.