The right tap is the one you like best. The impedance curve of the Sopra is pretty wild (but most modern speakers are) so no tap is 100% the best.
You can gleam some insight into the Sopra 2 by looking at the impedance curve vs frequency (link blow)
Each lower tap is a different contact point in the auto transformer output and as you go lower you cut voltage and bring up the current. It is best to match the load but when the load swings like crazy it can’t really be matched.
the short version is if you run the 2 ohm tap you get more power where the impedance is low but less power where it is high. With the Sopra being all over the place I am not sure it matters what you choose.
But really don’t over think it. If it sounded more open on the 8 ohm tap just use it. The Mac has enough power to plow through it anyway.
On a side note I think crazy impedance curves are why large powerful amplifiers sound better. Not because you need the power (again only using 4-5 watts) but the big amps just freight train right through these impedance curves. Where lower powered amps can really get tripped up over them and get hot and compress.
https://www.soundstagenetwork.com/index.php?option=com_content&view=article&id=1445:nrc-meas...
You can gleam some insight into the Sopra 2 by looking at the impedance curve vs frequency (link blow)
Each lower tap is a different contact point in the auto transformer output and as you go lower you cut voltage and bring up the current. It is best to match the load but when the load swings like crazy it can’t really be matched.
the short version is if you run the 2 ohm tap you get more power where the impedance is low but less power where it is high. With the Sopra being all over the place I am not sure it matters what you choose.
But really don’t over think it. If it sounded more open on the 8 ohm tap just use it. The Mac has enough power to plow through it anyway.
On a side note I think crazy impedance curves are why large powerful amplifiers sound better. Not because you need the power (again only using 4-5 watts) but the big amps just freight train right through these impedance curves. Where lower powered amps can really get tripped up over them and get hot and compress.
https://www.soundstagenetwork.com/index.php?option=com_content&view=article&id=1445:nrc-meas...