Maybe Leaving SET for Solid State because I want bass

@erik_squires This comment was made in the context of making measurements of an amplifier's output power. If the amp is high power, IME the line will sag as you run the amp up to full power so a variac is used to correct the line Voltage at the input to the amplifier to the Voltage for which the amp is rated. 

If this is not done the measured full power of a higher power amp will not be accurate. 

We have used a variac at audio shows, where line Voltage is often quite a bit less than it should be, in order to have our equipment running at the right Voltage. 

Parasound Halo JC 5.

or

Add a sub using speakon connection.

Mitch2 may be correct, why mess up what you already have accomplished, just add a good sub like Rel. After all quality sound is important for musical enjoyment as well. My problem is the opposite; I have too much bass and right now have no room to move the main speakers around. It sounds sensational but the bass although tight and tuneful is a bit too much on longer listening levels and I doubt if the neighbors like it either.

I always consider the quality of the bass and the quantity of the bass, and what you want.  Because you said you found a SS amp that provided the bass you want, I conclude that your speakers are up to the task if paired with right amp.  Hence, a sub or two may not be the right path.  I find it challenging to get quality, well-integrated bass with subs, even though you can get a lot of bass quantity.  I personally want quality over quantity.  

What was unsatisfying about the sound when you used the SS amp?   

One suggestion to consider is to get a pure SS amp with a tube preamp, or get a BHK 250 amp - which has a tube input stage and a solid state output stage.  I have two (one for each speaker) and it provides the tube richness and ability to tube roll, but a powerful bass.  It is only available used and its in your budget so you are getting it for 1/2 price retail.  This is specs from AI:

The output stage is high-bias, Class-A/B MOSFET design that delivers 250W/channel into 8 ohms and 500W/channel into 4 ohms. It uses only N-Channel MOSFETs for a near-perfect balanced waveform. The output stage runs in Class A for the first 20W, providing significant current for a "warm" sound, and it features a separate transformer from the tube input stage to maintain signal purity