Hey all! I have been doing some research on the HK AA-151 as I have been able to pick one up recently and am now contemplating what to do with it. The pics I have are on my phone, so I will post them in a following comment. I am interested in any first hand experience with this unit and/or its complimentary designs from the other makers of the time, IIRC the Dynaco ST-35 is an approximately equivalent design.

Google AI brief...

"The Heathkit AA-151 is a vintage tube amplifier praised for its excellent sound quality and charming nostalgic aesthetic, though it can be noisy and require maintenance, including new EL84 tubes for optimal performance. It is a point-to-point wired, ultra-linear EL84-based amplifier offering 28 watts of hi-fi power and featuring various input options like phono, tuner, and aux. While some consider its performance inefficient, with one user reporting poor results, others find it delivers a warm, sweet sound that is highly appreciated by vintage audio enthusiasts.  
Pros:
Sound Quality: Users and enthusiasts often describe the AA-151 as a great-sounding, warm, and charming amplifier, particularly when restored and with quality EL84 tubes.
Vintage Appeal: It features a distinctive and stylish look, often with a leatherette cabinet and chrome trim, making it an attractive piece for vintage audio collectors.
Build & Features: The point-to-point wiring provides durability, a significant improvement over circuit board construction. It includes multiple input options, such as magnetic and ceramic phono, tuner, and auxiliary inputs, as well as speaker outputs for various impedance ratings.
Restore-ability: The chassis and components, especially the Stancor transformers, are highly desirable, making the unit a worthwhile project for enthusiasts willing to invest in restoration.
Cons:
Noise & Inefficiency: Some users have reported the amplifier to be noisy and inefficient, with one user even calling it "the worst EL84 amp" they had ever heard.
Tube Dependency: To achieve its best sound, the amplifier often requires new EL84 output tubes and other preamp tubes, which can add to the cost of ownership.
Maintenance Required: As a vintage piece of equipment, it is common for the AA-151 to require maintenance and repair to function optimally, including cleaning of pots and switches and replacing old tubes.
Cosmetic Blemishes: While having a great aesthetic, units can show signs of age and use, such as scuffs, scratches, and discoloration on the finish.
Best Suited For:
Vintage Audio Enthusiasts: Individuals who appreciate nostalgic charm, sweet warm sound, and are interested in a piece of audio history.
DIYers and Restorers: Those who enjoy the process of restoring vintage equipment and are comfortable with basic to intermediate electronic repairs. "


So, with that being said, I am weighing the benefits of experimentation and modification vs restoration. This unit is soon to be packed away for a future time when I can properly address the project. I am starting the process of moving from the apartment I am in to another location, hopefully with a better workspace, when I can give this project its proper attention. I will not stop pondering, however, so I figured you all could ponder with me!

Specifications
Power output: 14 watts per channel into 8Ω (stereo)

Frequency response: 30Hz to 15kHz

Total harmonic distortion: 2%

Damping factor: 10

Input sensitivity: 4mV (MM), 200mV (line)

Signal to noise ratio: 55dB (MM), 65dB (line)

Channel separation: 35dB (line)

Valve complement: 2 x 6EU7, 2 x 6AU6, 2 x 6AN8, 4 x EL84, 1 x GZ34

Dimensions: 15 x 5.25 x 11 inches

Weight: 25lbs

Year: 1962

The tube set is all original (untested) Daystrom branded Mullard.

One of my uncles, an electrical engineer for GM, had one of these if not then a very similar Heathkit he built in the early sixties. I remember it sounding like Mrs. Butterworth, thick and rich, but the music he was playing mostly was sort of sweet soft pop instrumental music and I didn't really have many references to that type of music played elsewhere. Not at all like a Decware tube amp! I for several years before Decware had a similar EICO stereo integrated from 1959 and it too had a veiled and warm sound in comparison to the Decware Zen amp #27 that replaced it. . .I have a sentimental memory attachment to it, but I wouldn't trade any of my Decware amps for it now.

Rebuilding this with improved parts should be a fun and educational effort, and it should sound decent when complete.

I have a SA-2 Heathkit in my tech shop system. It was gone over by one of the local gurus before I acquired it. Mainly replaced some of the caps with orange drops. It has hum and may be in the need of tube replacement. I like the switching and input controls which are very similar to yours. The input jacks not so much, which are located on the underside of the amp. My power switch is integrated with the treble control unlike yours that is separate. Tubes are the same with a slightly different layout. My serves the purpose now, so no need to fool with it.

I'm not qualified to give any sort of opinion but will be following this thread with interest.

I have seen that this model is likened to the ST-35 Dynaco. I watched a side by side video of the st-35 and st-70 the other night on youtube... they sounded really nice. The demo was done with higher line Klipsch.

Can I expect similar results with this Heath kit or are there stark differences between the Dynaco and Heath?

That is sweet! I bet it picks up stations from the moon!

What bands does it pick up?