Cornwall IV – new amp vs crossover upgrade

While I don't have Cornwalls, my highly modded Klipschorns benefited greatly first from tube amps, both push pull and SET, 300B SET being my favorite pairing. My diy mods to crossovers also major upgrade. I couldn't live without both, but I'd say amp is place to start, whatever crossover mods you do won't be fully realized without the proper amp. Damping of horn is another good mod.

Yes I would say a nice tube amp and some solid copper speaker wires like AQ Type 4. Then work on horn damping and maybe knock down the tweeter if needed. They are not a very warm sounding speaker stock, more accurate than warm. A tube amp with the right tubes will sound very good, system synergy is key. I'm a bit of a broken record but my Rouge Sphinx might be as good as it gets for your system or a really nice tube amp. 

First get a good medium powered tube amp. I have heard horns, regardless of sensitivity, eat lower powered SET amps alive. Older Klipsch didnt present the amp with the best impedance load, but perhaps the new speakers are better. 

After getting a good tube amp then explore mods. An unmodified Klipsch is unacceptable to me but with mods they can be greatly improved. Actual Klipsch owners can steer you in the right direction regarding mods.

Thanks a lot for your replies. First amp, then mods then.

Thanks as well for the suggestions! Ampwise I have to take what´s available here (I´m living in Poland) and what I can listen to in advance. 300B I have to check, Rogue Sphinx is sold here. There also is a local brand, which is the one I could test already: Taga Harmony. Their HTA 2500B gave a nice first impression, but well, it was the first tube(hybrid) amp I listened to.

Since it may not be known here I leave a link below.

Per audition_audio, yes Cornwall not as high a sensitivity vs Klipschorns, but Klipschorns do have somewhat difficult impedance curve as well. My 300B monoblocks are sublime, but then they each have power supplies equal or surpassing what you see in stereo 300B amps. My 845SET or any 845SET for that fact should have no problem with impedance curve. Forget about most 2a3 or 45 for Cornwall, although 2A3 with really nice power supplies could possibly work. But for most, I'd agree, go with push pull. I previously had PrimaLuna Dialogue Four, damn nice in triode mode.

I've tried driving my Cornwall IV with a McIntosh MC275 VI, Rogue Stereo 100 with Dark upgrades, BoyuuRange A50 mkIII 300B amp, my Audio By Van Alstine 600R hybrid amp, and my Enleum 23R.  I own the last 2 and the Stereo 100 and the 300B amps were my friend's amps.  The MC275 VI was borrowed from a local dealer.  My 600R beat all the amps except one, the Enleum 23R.  The 23R was a class above all the others in terms of transparency, image clarity, soundstage width and depth, and musical engagement.  This amp has an organic sound unmatched by any other amp that I've tried. 

I won't go into details about its design because you can get that online and in several reviews.  John Darko recently posted a YouTube video rave review on the 23R.  Other reviews include 6 Moons in which Srajan said the 23R is the best solid state low powered amp he's ever tried.  As a bonus, it's a state of the art headphone amp as well.  It's not inexpensive and there's a wait list to get it but it's worth it imo.

I've not heard these, but if the new crossovers improves (i.e. raises) the minimum impedance or lowers the peaks it's probably a worthwhile investment.

Well if you want the best amp for horns but one that doesnt editorialize an OTL would be high on my list. 

...but my Rogue Sphinx might be as good as it gets for your system.

I quoted myself but I just wanted to add that on first glance you might think the Rogue is too cheap to match with the Cornwalls but it’s almost a perfect match, tube front end that you can tube roll to knock down the harshness plus 100wpc of class D to get things rocking and get control of that big woofer.

Crossovers are part of the design. You will change the voicing. Maybe better.. maybe not. Seems risky. 

I have concerns about fiddling with the hardware. That´s also why I asked about people´s opinions here.

What I take from the answers so far is that amp choice comes first. That seems to have the most significant impact in shaping the sound. Once I´m happy with an amp-speaker-combination and still find the speakers lacking, I may give modding a try.

Thanks for the suggestions which amp to try / which one is best. I heard about the Enleum 23R and find the concept striking. It just may be too analytical for my taste (on top of being just a bit too far out of even my inofficial price range) (but ask me about that again after I decide on something). I don´t have tons of hifi experience and was happy for a long time with my Audio Physic Yara II speakers, but the Cornwalls have shown me how much more music can breathe played on the right gear. I heard new things, which is amazing. And I´m sure pushing the lower frequencies a bit (or whatever the magic tubes can do is called) will make them even better to my ears.

The Enleum 23R is the opposite of analytical, think rich organic sound.  It performs on a higher level than the tube amps that I tried on the CW IVs.  I use the 23R as a power amp with my Van Alstine FET Valve CF vacuum tube preamp.   I also use a REL S5 subwoofer that blends perfectly with the CWs.  Two of the most difficult instruments to reproduce, piano and the human voice are sublime in my setup. 

I recommend that what ever amp that you buy, you either trial it first in your own system or buy it from a dealer that will allow you to return it.   All the amps that I tried sounded quite different from each other.  The amp that I thought would be my favorite match with the CWIV, the McIntosh MC275 VI (I used to own the V5 of this amp), was probably my least favorite.  The Rogue Stereo 100 was to forward and aggressive sounding even with my vacuum tube preamp.  The BoyuuRange A50 mkIII was soft and too laid back.  The Van Alstine 600R hybrid amp (NOS Mullard 4024 input tubes and MOSFET output) was excellent and only topped by the 23R.