Realistic SA-10: Just for fun
Yesterday, I bought a Realistic SA-10 (MODEL 31-1982) at the Thrift Shop for $1.06 including tax. It seems to work fine. The volume pots are a little scratchy, but only when I turn them. The SA-10 sounds pretty smooth on my Optimum 2B speakers, but beyond 12 o’clock on the volume, they start to distort. The speaker outs are RCA phono plugs. For a full test, I need to rig up some RCA speaker cables.
The SA-10 is listed as “New for ‘75” in the 1975 Realistic catalog for $29.95 . Joes Roberts  has a great description of it online. Roberts states, “I measured the power output of this amp and it can put out about 0.75 watt per channel with very low distortion”. He goes on to say that, "Radio Shack actually published specs for this small amp (they are listed in the owner's manual). Here are the published specs:
Power Output: 1.2 Watts per channel (at 1000 Hz with 10% distortion)
Inputs: Tape/Tuner and Phono
Volume Control for each channel
AC Power Consumption: 12 Watts max. "
Audiokarma member dinglebeer bought a SA-10 in 2006 . A 29 post thread ensued. Also on Audiokarma, it was nominated for "Smallest integrated amplifier in 2007  and suggested as the "Perfect amp for those Minimus 7's that everyone loves" in 2006 .
I got another audio WOW Sunday night. I hook up the SA-10 in stereo with my Realistic Optimus-2B speakers. I used the TAPE out of my Yamaha RX-797 as a source selector into the TAPE/TUNER RCA jacks of the SA-10. I used RCA phono cables to connect the SA-10 speaker outputs (RCA jacks) to the RCA jack inputs to the two 2Bs. I put the 2Bs on opposite ends of my desk about 44 inches apart and ear high when I sit in my chair. I sat about 24 to 36 back from the speakers which were toed in about 5 to 10 degrees.
I put Santana Borboletta in the Yamaha DVD-SD2700 and sat in the prime spot described above. I couldn't move- because the system sounded fantastic, great clarity and stereo separation. On the title track, Borboletta, I could hear the singer and the percussions walk all over the room. The SA-10 was sufficiently loud at about 11 o'clock on the volume pots. The 12 o'clock position was about the maximum volume I need for most applications.
The tone control on the SA-10 increased the treble slightly at its maximum position, but I preferred the neutral “straight-up” sound. The Optimus-2Bs have a 3 position “HF COMPENSATION” switch, NORMAL-LOW-HIGH. In stark contrast to the SA-10 tone control, I seemed to like the enhanced high frequencies of the “HIGH” position. I should diddle with the TONE and HF COMPENSATION controls some more to find my sweet spot.
For a buck & 6 cents, I’m quite happy with the SA-10. It’s a tiny little amp that really sings in the right application. It’s nice to see that my Realistic Optimus-2B speakers, which I bought new circa 1974, still have some life in them. I might look into recapping the 2Bs. Someday, I gotta get some DeoxIT to clean a boatload of pots, switches and connectors.
I think I’ll set up the SA-10/ Optimus-2B system as my desk computer sound system.