Nonsense! Zep 2 in one of the best recorded rock albums of all time and good copies hold up quite well to critical listening.
Correct -- but -- only for the first two songs on side one:
Whole Lotta Love and What Is And What Should Never Be
The rest of the songs have good sound quality, but nothing special. Side two also has good, but nothing special sound quality.
I have played my RL / SS pressing at Audio Connection, in Verona, NJ, USA, on their big system, each year when they have an open house, which is usually when a guest visits.
Richard Vandersteen visits every year. Others that I have met were Steve Guttenberg, Jim White (Aesthetix), Garth Leerer (Musical Surroundings), and a few others that slip my mind.
On one of Garth's visits, he brought with him Clearaudio's Goldfinger Statement cartridge. With that cartridge, my Zep II, RL / SS stamper was the most realistic sounding music I had ever heard. The musicians were carved out in a way that words cannot describe. My eyes and ears were arguing over whether or not I was in the room with the band.
The rest of the system was an AMG turntable (now probably a Clearaudo turntable), Graham tone-arm, Aesthetix Metis pre-amp, Aesthetix IO Eclipse phono-amp, Vandersteen's System Nine grouping of components, and Audioquest interconnects, in a treated room. I do not recall the model of every piece of gear.
When I was employed, I was able to indulge myself with White Hot Stampers from Better Records. I checked their site, multiple times a day, every day. When I saw that they posted an RL / SS pressing with their highest sonic grade, on both sides, I purchased it.
That was in August of 2015. The price was $799.99 (a steal by today's pricing, if you can find one).
Note that an RL / SS pressing only gives you a shot at amazing sound quality. I got very, very lucky.
I will be at Audio Connection in November, for their annual open house, and will bring that pressing, and a few other White Hot stampers from Better Records. Anyone in a reasonable driving distance can enjoy a real ear candy experience. You will hear Led Zeppelin like never before.
Note that the store's personnel might change their equipment. They will use Vandersteen's model Seven speakers, and the rest of the System Nine components. But they have recently been using Vandersteen's L5 ACC pre-amp, which is really good (but not as good as Aesthetix's Metis pre-amp, to my ear). It is a close call, but the Metis gets the win.
But when Richard is their guest, they use his pre-amp.
Also, they do not have a Clearaudio Goldfinger cartridge, unless Garth should happen to also be a guest and brings one with him. They have been using a Benz LP cartridge (or maybe the LPS -- don't remember). It is an amazing cartridge. Hopefully, they will still be using it. But nothing was as good as that Goldfinger cartridge with the Metis pre-amp (close, but no cigar). A properly dialed in Lyra Atlas cartridge would probably edge them all out (or so I've been told).