Grado calls the GS1000i its Statement headphones, and the "i" in its product name stands for improved - over the original GS1000 headphones released in 2006. This newer model looks similar but offers different transducers for what Grado claims is better overall sound quality.
For your grand, you get excellent sound quality to be noted for its detail and insight across the frequency spectrum, across all volumes - this isn't a set you need to listen to at high volumes to get the most from. The sound isn't hugely beefy as we heard in the PS1000 - in this respect the GS1000i are more what we've come to expect from an audiophile set. The bass is there, it's just lean and restrained. But it is also taut and punchy.
Dynamic and exciting but not out to impress with cheap thrills, the crystalline GS1000i sound demands an attentive ear for a full appreciation. The famous fab Grado mid-range is here, giving you that insistent forward sound, but the effect is less evident here than in some other Grado models.
The GS1000i can reproduce incredible detail, excelling at delivering the textures of stringed instruments and voices to your ears, like exquisite silverwear atop a silk cushion. With a high-quality source, these headphones are hard to beat, at any price. Their deep insight means that not only do you need to listen actively to appreciate these cans (calling them cans even feels derogatory), you also need a quiet environment - more so than the warmer-sounding PS1000.
If you put the GS1000i sound on a strict gym regime, to build up its bass and low-mids, you'd end up with something approaching the PS1000 sound. The PS1000 headphones are warmer, bassier and more powerful - but remember they cost around £800 more too. While we'd argue they are categorically better, it's a case of style too, not just ability. The GS1000 are less aggressive, more genteel performers.
With completely open backs - there's only a grille to protect the speaker housing - these headphones leak sound and don't protect you from the noises of the outside world, which is always on-hand to ruin your listening pleasure. If your double glazing can't quite keep out the sound of a nearby train station or pub, or your neighbours argue all night long, you won't get the best out of the Grado GS1000i headphones. If escaping these woes is your aim, you'd be better off with a closed pair of headphones, the Denon AH-D7000 being the obvious alternative choice at this level. Sacrificing sound quality over such mundane issues when spending a grand seems ridiculous though, so be sure your listening area is up to the task.
The other clear rivals to the Grados are the Sennheiser HD800 headphones, the "90s sci-fi" beasts to the quaint 50s sci-fi look of the GS1000i. Both offer superb clarity and detail, but the Sennheisers can be labelled as slightly clinical in their approach - the Grados cannot.
If you're willing to spend £1000 on headphones, you'll hopefully have already put some thought into what sets you should be looking at. There's no doubting the GS1000i are one of the best, with superb levels of detail on-hand and far greater comfort than you get with the more expensive PS1000 pair. A keen ear and a quiet listening environment are key to getting the most out of these headphones, but if you have those vital ingredients and a love of great sound, they're worth the investment.