[YJX94]

Thank you all for your answers.

Update:

I have received an Amp and...well the bass is definitely there.

In the end is the K712pro an upgrade to my 598? Nope!

The K712 sound is like filtered compared to the 598, but is more clean and well defined.
The 598 feels like I'm in the music but I lost some "details", these details are well highlighted by the K712.

So the problem is that I wanted to upgrade but in reality I have found something not better, not worse just different.
I will try the 990 out of curiosity before decide which one I will return.

990 will offer a very different sound signature again to the K712 and HD 598 but if you can handle the excessive treble then you might like it, they are very fun headphones.

 

[tomb]

The 50-Ohm HD598SE are very easy to drive.
The AKG K712 Pro is only 62-Ohm, but is more power demanding then a 250-Ohm Beyerdynamics headphone.
A Schiit Asgard should drive the K712 Pro, better than on-board audio.

^ this ...

The AKG 700-series phones are known for demanding a lot of current. Comparison with high-impedance headphones is not valid (referring to previous posts, not this one), because as noted above, power at 62 ohms requires much more current, not voltage, and the AKGs have never been known as easy to drive (like the HD595/8/9). Keep in mind that the bass will still be on the light side compared to many other phones, but they are able to go very, very deep.

I prefer the original K701 to the newer implementations (except the center bump!). I have a very-low serial number, original K701. I've also owned a K712 and sold it - likewise with the Massdrop K7XX version. Along the way, they took out the center dot covering the port at the back of the driver. It increased bass quite a bit, but a lot of the outstanding air and soundstage went with it. Massdrop added foam in the vented can (unless someone did it first with the 702 or Q702 - never owned those) and made things even worse, IMHO. The K712 never had the foam, at least in my version (Austrian made), but it just seemed like the distortion was pretty high, sounding "crunchy" on peaks. I could never listen to them for very long.

I'm going to keep my K701, though.

 

[YJX94]

^ this ...

The AKG 700-series phones are known for demanding a lot of current. Comparison with high-impedance headphones is not valid (referring to previous posts, not this one), because as noted above, power at 62 ohms requires much more current, not voltage, and the AKGs have never been known as easy to drive (like the HD595/8/9). Keep in mind that the bass will still be on the light side compared to many other phones, but they are able to go very, very deep.

I prefer the original K701 to the newer implementations (except the center bump!). I have a very-low serial number, original K701. I've also owned a K712 and sold it - likewise with the Massdrop K7XX version. Along the way, they took out the center dot covering the port at the back of the driver. It increased bass quite a bit, but a lot of the outstanding air and soundstage went with it. Massdrop added foam in the vented can (unless someone did it first with the 702 or Q702 - never owned those) and made things even worse, IMHO. The K712 never had the foam, at least in my version (Austrian made), but it just seemed like the distortion was pretty high, sounding "crunchy" on peaks. I could never listen to them for very long.

I'm going to keep my K701, though.

My made in Slovakia K712 has the foam ring piece in between the earpads and the drivers. The K712 is imo the best headphone AKG makes alongside the K371 and the K812 which is polarising.

 

[taigart]

Received the 990 pro...to my opinion inferior to the K712 pro, highs are too high, bass was comparable to k712pro.

I will keep the k712 thank you all for helping me.

 

[larson80]

Thank you all for your answers.

Update:

I have received an Amp and...well the bass is definitely there.

In the end is the K712pro an upgrade to my 598? Nope!

The K712 sound is like filtered compared to the 598, but is more clean and well defined.
The 598 feels like I'm in the music but I lost some "details", these details are well highlighted by the K712.

So the problem is that I wanted to upgrade but in reality I have found something not better, not worse just different.
I will try the 990 out of curiosity before decide which one I will return.

Pretty much exactly the experience I had when I upgraded from HD 518 to HD 650. Sure, the 650 sounds clearer and given optimal content, it just blows the 518 out of the water (as you'd expect). The problem was that for all-around use the 650 is just too picky. Just a pain with the bass renging from non-existant to great if it's mastered just right. Huge difference in sound quality depending on genre and mastering, I mean how much of Pink Floyd (with its great mastering/mixing) can you listen to?

I just found myself going back to the 518 that can't compete with the 650 in the optimal conditions. Because the conditions are rarely optimal for the 650 when you use the phones for everything, from gaming to jazz to metal to electronic. HD 518 did them all pretty damn well for 40 €. The 650 did much worse half the time and miles better the other half for 150 €. I guess that's reference headphones for ya.

 

[taigart]

Pretty much exactly the experience I had when I upgraded from HD 518 to HD 650. Sure, the 650 sounds clearer and given optimal content, it just blows the 518 out of the water (as you'd expect). The problem was that for all-around use the 650 is just too picky. Just a pain with the bass renging from non-existant to great if it's mastered just right. Huge difference in sound quality depending on genre and mastering, I mean how much of Pink Floyd (with its great mastering/mixing) can you listen to?

I just found myself going back to the 518 that can't compete with the 650 in the optimal conditions. Because the conditions are rarely optimal for the 650 when you use the phones for everything, from gaming to jazz to metal to electronic. HD 518 did them all pretty damn well for 40 €. The 650 did much worse half the time and miles better the other half for 150 €. I guess that's reference headphones for ya.

I agree indeed I'm hesitating to keep both.