Been using the Juntek DAP-1698 Dual Channel Power Amp as a AWG buffer, and thought others might be interested in a low cost Dual Channel Low Frequency AWG Buffer.
The design is based around a TI LM1875T power Op-Amp which is direct coupled input and output and has dual 26V power supplies from a XL6012 DC to DC converter and built-in fan which is noisy! Input power is 12VDC and supplied with a 6A AC to 12VDC converter. The LM1875 is a low frequency high power type Op-Amp that has a GBP, power BW and Slew Rate, 5.5MHz, 70KHz and 8V/us. The LM1875 design is a class A/B linear type output with overcurrect protection on both +- output current. It's heavily biased into the Class A for improved distortion, at the expense of static power dissipation with a nominal bias of ~70ma. Static PD is ~3.6 watts. Check out the data sheet on the TI LM1875, looks like a nice IC to base this around.
We just ran into an issue with the DAP-1698 going into a thermal limit cycle on both channels and suspected that the LM1875 was getting too hot because of an improper heatsink cooling. After removing the PCB, the two LM1875 were not mounted securely to the heat sink, causing a high thermal impedance and allowing the IC core temperature to rise and initiate thermal shutdown cycle. So the LM1875 IC did what it was designed to do and protect itself from over temperature

Once back together the DAP-1698 was fine driving a 100 ohm load at 40Vpp square wave or sine wave. Attached are some images and screen captures of the 40Vpp pulse rise and fall, 1, 10 & 100KHz sinewave and a 200KHz showing slew rate limiting. Also included a FFT of the output at 10KHz. Later maybe some tests at higher load currents if I can find some loads.
With the input shorted, the output measures ~20mvpp noise, ~2.5mv SD and ~6.5mv DC offset.
Anyway, hope this helps anyone looking for an inexpensive way to expand their AWG in voltage and current capability at DC & lower frequencies.
Best,
Edit I can confirm that the amp can deliver a 36vpp square wave into 33 ohms, that's ~ 9.8 watts!! Also can deliver ~0.9 amps peak before current limit kicks in.