It baffles me how someone can claim anything sounds good just because it comes from Sennheiser.It baffles me how anyone can even compare that Sony thing with anything from Sennheiser at any pricepoint. Or with any decent headphone for that matter.
Just to enlighten you, Sennheiser released a lot of rather bad sounding headphones in the past, ever heard of the MM-550X (probably the worst sounding pair of Sennheiser headphones ever made) ? The HD598? (although some like the neutral wide soundstage signature, but the lack of bass just makes them average sounding at best, and I am not a basshead).
They also did release great sounding products like the HD600, HD650 (though some may argue, sounds slightly "muffled" but that's because it pushes vocals forward, which is just a different listening experience in my opinion), the HD800/800S or even the (overpriced) HE-1.
That said, while the HD820 is decent sounding, it doesn't even get close to the listening experience provided by the Z1R (or even the HD800S for that matter), it's a decent pair of closed back headphones with a great looking design, comfortable and surprisingly lightweight, it's even good sounding (although, not impressive and nowhere near the sound provided by a HD800S or even a Hifiman HE4XX, and that's a $170 pair of headphones!), Is it worth its €2000+ pricetag? Hell no! I Daresay you can shed €1000 off that price to get anywhere near what would presumably be a good deal (and it might even not be, considering you can still get the much better sounding MDR-Z1R (which to be honest, has no contenders when it comes to closed back headphones at this time), or the HD800S (still much better sounding, despite the HD820 being based on the HD800S design!), or even a much better sounding pair of electrostatic headphones such as Stax along with an Energizer to drive them!
Quite frankly, you probably never gave the Z1R a good listening or you wouldn't be trashing it. Yes, Sony has not always produced good sounding headphones, in fact most of them don't sound good at all, I daresay you don't want to invest in the MDR-1A or MDR-1AM2 which don't sound good in my opinion (and I do own these, I even drive them over balanced!), the MDR-Z7 are decent, although you can get better at an equivalent price range, they also do produce some pearls like the XBA-N3 (which are great sounding IEMs at an affordable price) or obviously, the previously mentionned MDR-Z1R.
If you can't have an objective opinion, that's your problem, if you want to spend €2000+ on a subpar/average pair of headphones, good for you, I for my part, will be spending my money elsewhere.