Vinyl sounds a bit thin and slightly strident.

Parts Connexion/Canada discounts Mundorf caps. Silver/Gold/Oil is Mundorf's new top model. I've been using Silver/Gold (non-oil)version-- it's a great cap but may not have the midrange and LF bloom that you're seeking. You will find these quality as well in the Mundorf Silver Oil cap. I can't recall the values used in the PH-2, but they may be fairly high-- which can get pricey.

Texas Components TX2575 resistors are available directly from TC on a quotation basis @$9-$11. You might want to first try replacing loading & several resistors at input and after listening, work further into the circuit. These .5W metal film resistors have the rare combination of high resolution, sweetness, & warmth. Too expensive for most hi-end manufacturers! Once you try some, you may just forget all about tube rolling and IC upgrades...

I have owned Benz cartridges and ARC phono stages, I agree with most of the comments so far.
First, Benz cartridges excel in the midrange. Do not expect great bass punch from a Benz cartridge. Treble can become desimbodied from the midrange if the VTA or VTF are not spot on. Benz VTA is tricky, as is VTF, due to the narrow stylus profile.
Second, Sony players in general have outstanding bass quality, it will be tough to find a phono combo that will beat your Sony in bass slam...more natural / organic bass is possible, punchier bass is difficcult.

A few suggestions regarding brightness and lean sound:

-Valhalla wire, the transparency-champ! It sounds very detailed and lean. It may be a great choice in the right system or may ruin the tonal balance, specially because it is the first cable in your system.

-EH tubes - I agree with the previous posts, they sound harsh and forward as compared to good NOS tubes.

-Cardas Hexlink is not as full-bodied as Cardas GR or NR.

Lastly, leave the phono preamp on 24/7, it will sound much smoother after a couple of days of warm up.
Good luck

Dgarretson provides good input on the TX2575 resistors. I just replaced 22 resistors in the audio section of a Counterpoint SA-2 with TX2575 and the clarity was greatly improved. I can relate to all the praise that Michael Elliot gave to these resistors when he compared them back in 2007. However they had little to do with the SA-2's incredible portrayal of space which is inherent in the SA-2's overall design. And I suspect such changes here will not be as beneficial as tube rolling (in the LS7) for the improvements in bringing more life to the mids.

Until you get those EH tubes out of the LS7, all the fiddling with cables is only going to result in one set of strengths/weaknesses for another.

I can not suggest a specific 6922 tube for the LS7 because one tube type might be so incredible in one product but be outperformed by another tube in another product. I have no experience with the LS7....only the LS5. And I did not go through the multitude of tube-rolling efforts with the LS5 like I have with other products since I owned the LS5. But the Amperex quite handily outperformed the stock ARC tubes in both the LS5 and the SP-10 that I had before it. There is so much to gain from the trials and patience of trying many tubes in each component.

The Tele 6DJ8 is the king in the SA-2 but in the Aria WV preamp, the Amperex 6922 works like no other. And in the CAT amps that I use, a number of Valvo, Philips and Amperex all work incredibly well; the Telefunken was not a good fit at all here with the result being a most flat presentation. Without trying these in each product, there is just no way to know.

From a view of the circuit board on the LS7, it looks like 2 of the tubes need to be the same but the other two you could try different brands. Maybe try an Amperex 7308 for a little more detail and dynamics and the Tele or Amperex 6922 for more midrange smoothness and bloom.

Once you get a set of tubes here that take the performance to the next level, the IC from the LS7 to your amp will be CRITICAL to achieve that next level of 3D performance.

The variety & multitude of suggested corrections & mods seems fairly overwhelming; who knows it could be any, or a combination, of the above.
One area I haven't seen addressed nor do you mention, is what AC cables you're using. Since the CDP is satisfactory, you might experiment with upgrade AC cord on the phonostage alone. Or line conditioning. Perhaps even footers or an isolation shelf. All of these can change sonic signature to a lesser/greater extent, especially with tube componentry.
Some here would argue that cabling & cords can't possibly affect the sound of a component. However my own tuning experiences with changing AC cords (and to a lesser extent, line conditioning) have proven that a world of difference can certainly be realized.
Just another mystery to throw into the mix - sorry ;-)

I have a question about effective arm mass and loading at the end but let me start by saying this.

Bob, I'm using stock cables on all my gear. The ARC stuff does not have user removable AC cables and I'm not planning on delving that far into tweaking by removing the stock cables at the moment. The only device I have concerning power is a Furman power strip that everything is plugged into. I am familiar with the benefits of using power devices having borrowed one to try on my system in the past and I'd like to own one in the future.

Jafox/Dgarretson, I like the valuable information you've written. I will have to keep your posts close so when I'm going to plunk down some cash for new tubes I have some sort of reference. Plus I'd like to give the resistors a try. Thanks!

The cartridge is 9.5g and it's looking for a medium to high mass arm according to Benz's spec sheet. However, I'm not particularly sure what the JMW 9 Sig. arm mass is. Also, I've figured out that other than light bass there is a response bump at around 3.5K that gives music a more tense feel. I'm sure it doesn't help that the most sensitive area of hearing lies right around that frequency. My question is will changing the loading resistance help this bump? I'm loading at around 2.5K/60pF(cable capacitance), the cartridge Z is 95ohms, Benz says load >1000ohm but I've heard about a 2.5/1 loading ratio which would put it @ 237.5. What should I expect if I drop loading to that even though Benz suggests 1K minimum?