I have read this thread in full with some interest even though I have moved to 'serious' LP replay since too recently. I write only to tell you that in my opinion nobody will have concretely positive help or advice to offer, because nobody has your ears and your room and your taste. You have very rarely written to me about your vinyl life because I wasn't into it enough, having only a secondary system in the studio with nostalgic 40-odd years old gear to replay 40-odd LPs when days were unbearably grey and insignificant.
Then I bought a decent TT – sorry, nothing British: a Pro-Ject RPM 3 Carbon, which, once setup with a minimum of care and placed in the main and now only set, turned out being much better than my expectations, with a Grado Blue 1 MM cartridge and a Stageline N. To me, it all sounds good, very good, but depending on three things: mood, expectations and quality of the LP. I have 50 years old mono LPs sounding lively and engaging, and modern 'audiophile' pressings that only show to which level of foolishness the world of audio has dropped, and how miserably we throw our time down the toilet in infinite indecisions, regulations, tweaks, changes of opinion on practically every single piece of our stereo systems.
Now the Allaes are the culprit. You write 'ploddy', I go and google the word, find nothing and must go by nose. Or it is the cartridge, and here I have nothing to google because I don't know anyone of the quoted ones. I only know my Grado, which was a cheapish model when I bought it but these days it was tracking every inch of any disc without distortions or indecisions. 1,65 grams. The funny thing – please forgive me if I refer to our private correspondence for a moment – is that when I wrote to you that I didn't like the idea of two different sources in the same system – LP and CD – you were always very encouraging and full of arguments in favor of also having LPs In the living room; now I have both and am satisfied. But then, you wrote a number of times to me complaining how you seemed unable to have sound of your complete satisfaction with either LP or CD in the same system! Proof of this, the SBLs – which, in my opinion, are to Allaes what Orson Wells is to Guy Ritchie – went, and Allaes came. You say they can sound ploddy; I don't know what that means, but I have heard Allaes several times and always found them the most assertive (let's not say aggressive not to hurt anyone in the Headquarters) in the mid/treble among all the Naim speakers I have heard or owned. It seems to me that you want the right sound with CD, LP and Radio in a single speaker system. Impossible?
My SBLs never sounded wrong with CD. When I sold something, it was never because of sonic dissatisfaction, with the single exception of the very first S-400s but mostly of the SuperUniti, which I hated from the first minute I had it. Don't ask me why I bought it. One of those moment of craziness – many here have had them, trust me – when you believe that you can have a one or two box solution in NaimWorld: which is impossible and a nonsense, unless you are one of the very very few lucky guys who really are content with plain good sound and who really enjoy music, not the system.
Naim is for multiplicity, and the impressive compatibility within the range is made to encourage multiplicity, not to favour reduction. I am really sorry not to be able to give you any positive help or advice, but I have a feeling that you won't solve any issue. I may be with Bob the Builder, and predict a change of speakers within one year. I don't know how you can be happy with Allaes. Did I mention one of our mutual acquaintances, who has a sci-fi 500 system with S-600s and is sometimes doubtful about it, and has had a UnitiLite + N-Sats system for a while that was a joy for the ears and peace for the mind? Guess which of the two systems went?
The member who suggested a used HiCap on the Stageline might have a point, if we accept the idea that the Stageline is 'bright'; but you say or imply that the Allaes don't guarantee tightness enough to vinyl, so a HiCap, that brings a few Kilos to the sound? My Stageline has actually some 'verve', but that is good with the Ovators. The Grado and the Pro-Ject, for some miracle, seem to sound much the same. I am lucky, but most of all I have set limits to my expectations and budget. Plus, I have decided to subjectively and intentionally like certain things, instead of hoping to find the miracle combination of their objective goodness. This saved me.
Please don't be offended if I posted all this publicly instead of keeping it for our daily, entertaining private correspondence; but in my opinion you are not considering the only lifejacket that could save you from perennial paranoia, which this forum won't ever help you dispelling, since everyone has a suggestion for things, people, places and sounds he has never heard as they are as an ensemble: an asylum. I am referring to compromise. Smell your cart, your phono stage, your deck, your amp and your speakers as you'd do with roses; the ones who don't smell enough, sell them. And go back to daisies.
All the best