will changing to solid-state make the bass in my wilson sophias better at low volume?

I've noticed that my sophias really shine when they're cranked up a bit, which is great, but I'm wondering if I can't get more of that, esp. the bass, at lower volumes. my tube amps (Cary Slam-100s in triode) are ~50w/ch, more than the 25w/ch minimum wilson recommends. it seems to me that I could either get a sub or try a solid-state power amp. it'd be easy enough to try either/both, but I'm curious what people have to say. thanks!
You need a good old fashioned loudness control.
I have remote volume on my sub array for lower volumes. And three EQ units. A mini DSP has 4 presets you can setup for different levels.
I'm using itunes, which has a 10 band eq. I tried using that, but didn't like the results.
I second the "loudness control". 
I have Sophias also. I use my McIntosh equalizer to make a great old fashioned Loudness control. Just go along the Fletcher-Munson loudness curve.  On the McIntosh that means the most boost at 25hz, less at 50hz, least at 100hz.  Anytime I am not listening at full "audiophile" volume I have the equalizer on and it sounds great. At full volume the equalizer is not needed.

S.S. usually doesnt have good low volume detail which is a area where tubes shine. Odd to me that a speaker would not sound good at low volumes but "better" at higher volumes. 
thanks for the responses. I'll play around with the eq on my itunes, see if that does the trick.
IME, tube power will produce full and detailed bass but SS can produce more sharp edges. Tubes have a more loose sound but also more real. If you like that SS sharpness, try it. My preference is tubes.
Leave it alone and get a couple of sealed 8 - 10' sealed port (small) subs and be very happy. I NEVER use tubes for bass in my main system. Just doesn't work.  25-50 watts will do great from 60-100hz and UP.

Below that is the BLOATED BASS issue typical of valve amps.. SS is always better. You can't EQ what you don't have without a SQ price. HEAVY bass really taxes valve amps. They do pretty good doing one or the other but both, not so good. Easy fix.. Get a little sub an place it right under your rump. :-) No just kidding.. though that is close.. maybe right behind your chair.  OR A pair right behind on either side.. close to the side walls. No ported though...Want to get fancy servos.. 8-10" yup.

@musicslug , look up Fletcher-Munson curves. This explains your problem. This is why people are talking about a Loudness Control. It kicks up the bass and treble bit still thins ae "right" at only one volume.
I just prefer to turn it up until it sounds right. 
Subs can get you there for sure. Buy a solid SS from a company that has a trial period and see what happens. Personally, I like the set and forget approach. Constantly changing settings would get tedious to me after a bit. I’m all about finding a sweet spot and letting it be. The only way to find out for sure is to audition a few amps. Your current tube amp may not have a high enough bias to drive your woofers well at low volume. Maybe play with that if you an adjustable bias setting.
thanks again. this is all very helpful. I'll probably try a subwoofer in the near future...
Tubes are great for preamp use, but solid state amps control the bass much better. I have had some very good tube amps and none of them produced quality bass, too sloppy. I would stay away from loudness controls, I’ve had a couple in the past. I had the same problem in a smaller room, low volume, no bass, turn it up for good bass, too loud. Got a couple of rel subs and tuned them for low volumes and they still worked when the volume got louder. Now you can get remote controls for your subs so you can adjust the bass for any volume
Why not install Amarra Luxe, as it works on top of iTunes? It sounds TONS better than iTunes, and also has a number of choices for digital tone control, including various curves optimized for various kinds of music. It also has digital volume control, and allows for over sampling and for MQA full unfolding. 
Always had this problem. The first octaves to cut out as you lower the volume is the low bass. I finally spent a few bucks more and got a much more powerful amp. It is SS and it is rated above the max of my speakers wattage, but now when I lower the volume octave to octave it is still present. No loudness even exists on my pre-amp. I am using 500 watts into 4 ohm nominal speakers, rated at 300 max. Just an observation that is a first, and a pleasant discovery indeed.
Presumably you have optimised speaker placement -- if not, you could be losing some bass energy due to placement.Sophias output a reasonable amount of (upper) bass.
Otherwise, missing bass at low amplitude also means your (all of our) ears are less sensitive to lower-mid and bass frequencies (Fletcher-Munson curve) as mentioned above.
Once I demoed the Sophia 3 with a musical fidelity A5 (solid state integrated amp) back to back with a $30k AR tube pre and amp (model?). The tube setup lost most of the dynamic bass slam that I found intriguing on the A5. The bass had crazy slam and power on the A5 in a very large room. 
Maybe try a cheap use solid state amp, even a class d just to mess with. If you like it sell it and get a good solid state amp. It is alway a compromise somewhere though. Expect highs to suffer.
I guess I just need to audition a high-powered SS amp and a (sealed) sub in my system. thanks for all the helpful responses, especially from people who have experience with sophias.
I have Wilson Sasha 2 speakers and also have had some issues with tube amps and bass control. I think that you received some great suggestions, including adding a subwoofer, using a loudness control,  and trying a more powerful tube amplifier.

It probably is my bias (pun intended) and the type of music that I enjoy (violins, violas, and strings) but solid-state amplifiers are not a good solution for me. I  recently tried a Luxman M900u ampilifier and a D'Agostino Momentum S250 amplifier, and although they were both great, I could not live without the mid-range timbre provided by a valve amplifier. I now use Audio Research 250SE monoblocks along with a Luxman CL1000 preamplifier (and an Esoteric X-01XD SACD player).
The Sophia 3 has a woofer damping resistor under a cover plate at the base of the speaker. Changing this resistor to a higher value will reduce the woofer damping and allow it to produce a fuller bass at all volumes. Not sure about Sophia 2 or original. Worth it to check.
Firstly, I have no experience with either your amp or speakers. That said, I notice you are trying for more bass with a  triode amp. I suspect the triode will not give you that bass because they usually cut off the bass in favor of midrange emphasis . So, IMO FWIW YMMV you may be trying to get something a tubed triode amp does not readily give.
Second, I've heard all my audiophile life that SS gives better bass. So you can imagine my surprise when I bought my 1st tube amp  about 12 yrs ago and finding out it did BETTER than the SS I had been using the previous 40-50 yrs. Yes, the bass is more "flabby". But having played drums in local bands for 50 yrs, I can tell you that the tubed bass sound more realistic to what I heard while playing with a live bass player (Classic-hard rock). My latest amp, Sachs Kootenay 120 does great on bass...and midrange 7 treble too. I doubt I could go back to SS now.

“I guess I just need to audition a high-powered SS amp and a (sealed) sub in my system”

@musicslug, Before you buy a sub, try a high quality SS Integrated. I suggest Gryphon Diablo 300 that would pair well with your Wilson’s.

I am also of opinion that no full range speaker is capable of producing deep textured low and mid bass that you get from a high quality subwoofer (REL’s) unless you’re using a full range speakers with built in powered sub (like Vandersteen’s).
You are battling against a speaker efficiency of 87 dB vs 92 dB on larger Wilsons, so you need a higher output tube amp to tame the Sophias.

I use a 70 wpc tube amp on the more efficient models with no loss of bass control compared to a 300 wpc solid state amp I used to run them with.  If you get the chance, try both a more powerful tube and and an SS amp and see what you think.
The subs are a no brainer. I have two RELs and they really help out the bass at all volumes. You have to turn up the amp so much to get those divers moving on your front speakers. Not the case with subs. Next is the type of amp. Mark Levs have to be turned up so much before the bass engagement. On the other hand the Ayre AX5 integrated amp provide great bloom at all levels. Last is the preamp. I demoed the Rouge RP7 balanced preamp and it was so great at providing that bloom at very low volumes. This is with a SS amp. There is something awesome about a tube preamp with a SS amp. Like yin and yang. I am auditioning the Rouge RP5 preamp which has the phono preamp. Something very cool. You can turn the Phono preamp input into a line input in case you want to use your own phono stage and it has extra preouts for subs. Rouge is really good. If there is a Rouge dealer near you try out some of their gear. If you are in the Chicagoland area check out Holm Audio. https://holmaudio.com/
OP, look here first and gather some good information.

Servo bass units..


With Wilsons.. Gotta be a good combo. Understand me, I know NOTHING about Wilson. I have two friend that are Watt Puppy fans. They have done everything to those things.. Wonderful speakers. They are SS bass and Valve mids and highs.. That took a bit of sorting..
All Mcintosh. MC275 and MC2300 and an original C22 all dolled up on one. 5 years ago..

BUT for you

A pair of 8" or 10" sealed servo. Talk to the rep it will be a Cubic Foot thing, and how you want to pressure the room.. alway add 2 more, Servo is REAL nice. Little boom BOOM in the Room ROOM.

Wilsons require high current amps to drive them properly. Also, triode is not the best mode for dynamics at any volume. Do you have an ultralinear mode on the amp that you can switch to?
In my Wilson travels (Sophia, WP7s, Sasha and now Alexia 2s), I have found that high current tube amps with 100 to 150 WPC are enough to push all of the above to satisfying dynamic levels. 250 WPC or more are even better. But at 75 WPC, it will depend on the manufacturer. Audio Research Ref 75 worked pretty well. Can’t say I know Cary well enough to render an opinion about the pairing that you’ve got.
I personally prefer Wilsons with all tube amplification. The bass is different than ss but sounds more live to me. But that’s just me.
Taking a different tack, I had been in contact with Ayre due to bass complaints with my amp. Since they had no off-the-shelf mods for that unit, I looked to other factors. Long story short over several months, I found that for better bass in my system controlling the vibration for the equipment in the stereo rack helped immensely. I used IsoAcoustic Orea pods under amp, iso transformer, and DAC vs. blocks, cones and other options. Would have added a set under my Ayre pre but i have no vertical room for it. Second,  testing different DC power chords between Uptown LPS 1.2 and Ultra Rendu, and keeping it cheap (so far) to improve bass, I ended up with with Cable Matters, written about extensively in different forums. These seemed to give the power back to the bass region, though they were not perfect. Third, were better PC's. I use Cerious and each new chord beefs up the bass naturally. And fourth were improved plugs from the Topaz Iso Transformer to the wall, and for the charging unit for the EtherRegan. So, no equipment changes and i got improvements that probably needed to be made anyway that were somewhat close to an amp change. 
I should add that before any of this, I spent several days retesting speaker placement and due to the first and second changes above, retested again and might slight movements. It all matters. 
I have Sophia 1s and have had them paired only with ARC tubes with excellent bass response.  I went through a few different separates systems with a pair of Classic 120s and then a REF 150.  The REF 150 improved the bass response slightly over the 120s with better overall sound.  I now am running the ARC GSi75 integrated with great results.  I am using a pair of Hsu Research TN 1225 subs crossed over at 43 Hz with the Wilsons playing full range.  They blend perfectly and it sounds amazing.  I used to have a goal of getting my system to where I could disconnect the subs but now realize that they are a great addition to any 2-channel system.  Regardless what amp or speaker you have today, tomorrow or 10 years from now.....a good sub will always help in your overall delivery.  Good luck!!
...I wanted to clarify and add on a bit more to my previous post. 

I initially listened to the Sophias with all those amps without the subs with great bass impact.  

I had listened to my previous floor standing speakers with B&K and Parasound amps and always felt the Classic 120s provided better bass response.  

I know this is a sensitive subject and many are adamant that solid state will always provide better bass, but I believe my ears and regardless what the specs dictate the bass from quality tubes amps is beautiful

I still have the same recommendation but you know....YOU are curious.  Go ahead and find a used solid state amp here on Audiogon that meets your criteria and check it out.  Maybe your ears will like it better!  If not, resell and then you will feel better about your Cary amps and be able to put that to rest.  The seed is planted so if you are like most of us you won't be able to let it go until you actually get a solid state amp in your system...and that's half the fun!  That's what we do, right??  

Have fun!!!
Try improving  speaker position.  Follow the WASP system. If that fails consider amp change. Maybe try Pass Labs 
Darko's A500 Review notes a setting that tilts Highs / Lows at low levels.
"  Buchardt’s ‘Low-level Enhancement (LLE)’ corrects for the Fletcher-Munson effect where, at lower SPLs, our ear-brain is less sensitive to low- and high-frequency information."
let's worry about the mids 
in the speakers first. 
   Let's get that right 
Loudness contour adjustment. This is not a fault of your equipment but a result of what is referred to as the Fletcher Munson Curve.

At lower levels the 3k - 4k range appears louder than the other frequencies especially the lower frequencies. This is just part of being human and physics...

A loudness contour control adds the appropriate amount of EQ based on the level you are listening. Most notably at lower levels you need a 10dB boost on the low end frequency to make everything sound in balance.

Maybe try one of space tech labs virtual subwoofers. It's not a subwoofer but a lot of user reviews say it sounded way better than some top quality subs like rel with better integration. Their is a thomas and stereo youtube video of a pair of 60,000 speakers and the owner is using one of these. I have no experience with this product but I do own one of space tech labs preamps and it has very good sound.
If you add even one good powered sub, JL Audio or REL you are adding 1000 watts or more of SS power to your system.  And you keep the beauty of tube amplifiers. Sure get a bigger tube amp over time but the sub does what you need right now in one easy step.  I'm running Yvettes on CJ Art 150S tubes and a JLAudio F113 sub.  Enjoy.  
Look for a Wilson Audio WATCH Controller or a JL Audio CR-1 Subwoofer Crossover. Bryston makes a 10B Crossover as well for my third choice. These items are incredible. I’m currently using the Wilson. One of the best pieces of equipment I’ve ever bought. I’m using them on the Wilson Maxx 2’s with a pair of JL Audio Fathom 113’s. I have complete control of my system. Totally dialed in. You may have missed the steel of the century because someone sold a Wilson Audio Watch Controller for $450.00 today. Unbelievable!

has it right, all most all systems needs subs but an active crossover is key.