It was the output tubes all along...

@orthomead  Etymotic makes great products. I have been using their ear buds for decades and always take their attenuators along for every concert. I insist on people using hearing protection in my shop. Having said all this the recommendations of "authorities" are always on the conservative side. The worst hearing exposure and the most likely to do damage are loud impulse sounds such as gunshots. Steady loud noise gives your ears a chance to tighten their ear bones ( stapedius muscle) and provide natures level of hearing protection. I never start out at 95 dB, but turn it up slowly over a song or two. 95 dB is also the peak level. I am 70 years old and can still hear 16 kHz. I've been rocking since the age of 13. I am also an anecdote. There is a genetic sensitivity to noise induced hearing loss.

@orthomead 90 dB is pretty loud! The loudest I listen is 95 dB. The reason to use the bass management I previously discussed is to create the FEELING of a live performance a less than ear shattering volumes. It is, in large part, the visceral component of frequencies below 100 Hz that make live music so exciting. 

I was over a friends house two days ago. He has a wonderful system. Serblin K'tema speakers, CS Port turntable, MSL Signature Platinum cartridge, Bricasti amp, DAC and transport. We were listening to, of all things Vini Vici (disco dance music with heavy synth bass). He pulled his meter out and it read 104 dB! I had no idea it was going that loud. I played the same cut at home and 95 dB blurred my vision. My friend, having had a bad experience in the past, will not use subwoofers and the fundamentals of the synthesizer bass were AWOL. He is beginning to warm up to the idea again. 

Staying on topic, with a proper subwoofer system you can drop back to the KT88's better sonics and still have a much more powerful system than you would with KT170s and what you are presently doing. 

@mulveling That 20 Hz rating is at one meter. They do better than most speakers, but the issue is that you have to boost 20 Hz 10 dBSP to get the right balance. This will push the S7's woofers into their nonlinear zone at rock and roll volume increasing distortion. This will also torture the amp. Breaking out 100 Hz down to a dedicated subwoofer system decreases distortion in the main speakers and allows you to get the proper boost without torturing the main system. 

The issue for many audiophiles is digital phobia. They stubbornly want to keep their system pure analog in the belief that it sounds better. In reality the benefits of moving over to a digital preamp/processor are legion. Conversion to and from 24/192 digital is now invisible. Once you are in numbers you can do almost anything without added problems such as subwoofer management, EQ, room control and high resolution steaming (Qobuz). The benefits for outweigh any detriment if there even is any. The best digital preamp for you would be the DEQX Pre 4 which is still in Beta mode, but the prices are still about 1/2 of retail. My friend with the S7s just got one. We have not set it up yet. The best value is the MiniDSP SHD. Down the line you can add a high end DAC for your VAC amp/S7s. The SHD is only 1500 with the best microphone. Add two Martin Logan Balanced Force 212s and you are in business for a total price of just over $10,000. The 212's are handily the best value in subwoofers today. With the SHD you only need a CD/SACD transport like the Bricasti M19. The SHD is set up to stream Qobuz which IMHO is the very best streaming service. It also uses Dirac Live, the easiest room control system to set up. My guess is that this addition will blow you away and you will wind up getting the DEQX which matches the quality of your system. It also has a fine phono section in it designed by Dynavector. It is designed to use a transformer for low output cartridges. I have a Pre 8 which is the identical unit , but with a 4 way digital crossover for people who want to triamp their systems. You can make any loudspeaker fully active. I would leave the S7s alone in this regard. Magico knows what it is doing. You want the Pre 4 which is somewhere around $7000 now and will retail for $10,000 I think. This would make adding subs a total of almost $20,000, but you won't need to buy a better DAC. Financial advisors always think HiFi is a waste of money. I do not bother mine with it avoiding the argument all together.  

@orthomead The KT 88s are more crystalline for lack of a better description. With proper subwoofers they will really sing. You have a fine turntable. Do you listen to any digital sources? By proper subwoofers I mean a subwoofer system that can be crossed at no lower than 80 hz and be able to put out a 20 Hz test tone at +10 dB from your loudest listening level  Duke has a fine system, but I am afraid it is a bit lost under S7s. Your VAC and the S7s will be A LOT happier if they do not have to deal with low bass. Separating the low bass out allows you to add the proper amount of gain to approximate the kind of bass you get at a live performance. Do you listen to any organ music? 

A system that is ruler flat in a residential room sounds awful. It will be way too bright and almost bassless. The right curve for this situation that most of us find ourselves in has 20 Hz at +10 dB over to 40 Hz at +10 dB then down to 0 dB at 100 Hz. I like a little 1 dB dip after that to 150 Hz, but that is personal preference. It makes the bass a little drier. From 100 Hz you go flat to 1000 Hz then start a slow taper to 20 kHz where you should be down between 6 and 12 dB. The louder you listen the more pronounced you want this. Every recording has a "right" volume, the volume it sounds best at. Too loud and it gets harsh. Too soft and it will be dull. 

If you have EQ capability you can force your S7s to do this, but the VAC will not like it at all. This is one of the two main reasons subwoofers are important. They are designed to make low bass and you can push them to the right volume without punishing the rest of your system. Even better is using a two way crossover to remove the low bass from the VAC and S7. The system will cleanly attain a realistic amplitude response at a volume that will make you feel as if you are at a live performance and I do not mean ear shattering either. To give you an idea, my speakers will not go as loud as your S7s. They sound bigger, but not louder. I use eight 12" drivers in four enclosures, each enclosure getting 2500 watts. Using fewer drivers would result in more distortion. Your Swarm has four 10" drivers. Two 10s equals one 12. Under a speaker that is capable of more output than mine you are using a subwoofer system 1/4 the size. 

Finances are an issue for most of us, myself included and Rome was not built in a day. You have a great start in the S7s, VAC amp and turntable. The Ultra Eminent is a super fine cartridge and the sweet spot in MSLs range. They are about to release the Signature Diamond for $15,000!  A good subwoofer system that matches your speakers will improve your sound quality eons more than a new cartridge. 

@jasonbourne71 1+

However, the S7 has a very flat 4 ohm impedance curve. You probably still have a lot of room for improvement. A good friend of mine has S7s. I am working with him to get the best out of them. I think you should try KT88's and I would match them even though your amp does not require this. All 8 should match! Small differences in amplitude response will affect imaging. Another approach, the one I take is to measure the system by channel at the listening position, but I have the ability to correct any amplitude problem, you do not. The amount of power your amp makes is totally dependant on the power supply. With KT88s in mono configuration your amps put out 200 watts which with subwoofers is more than enough to do the job.  

The swarm is a great system for bookshelf speakers. It is nowhere near powerful enough for for the S7's. You need at least four 12" drivers. Two Magico S subs or two Martin Logan BF 212s would do the job. My friend has four 13" JL Audio subs which I am not crazy about because of reliability issues. I believe the S sub has a complete crossover in it. The BF 212 only has a low pass filter like your swarm. This is not satisfactory particularly with your amps. You need a complete two way crossover with complete bass management. I would put the subs outside the S7s in corners. This only works if you can correct time and phase. I would cross at 80 Hz. What are your program sources? 

Done correctly, your system will be able to play Vini Vici at 100 dB and blur your vision or the Melos String Quartet at 85 dB and make you cry.