Are the KEF Blade/Blade 2 Metas a Significant Upgrade from Blade?

It seems the input sensitivity and the output impedance of the 175XD and the 300XD do not match. So my only option to bi-amp would be a second 175XD. 

????????????? I just looked up the specs on the 175XD and the 300XD and the gain is exactly the same....26.2db. They will play together perfectly. And the output impedance is so low in both of them that it won’t have any effect on gain or frequency response as well. You are good to go....unless there is some other issue.

Input sensitivity means how much input voltage gives full power from the amp.....since the 300 can put out more power then you need more voltage to get ALL of its power.........What is important is the actual GAIN of the amps.....and they are the same.....so biamping with them is perfectly fine.

Well I read the part about input sensitivity and output impedance on the internet. I thought everything on the net was true.

Bi-Wiring and Bi-Amping Explained - How To Improve Your Audio Setup | Audio Advice

Your post is encouraging I also asked KRELL today the same question. My CODA 07x preamp also has dual XLR outputs so I can easily send 2 stereo amps the same signal.

If two amps have the same power rating......then the "sensitivity" would matter and it would imply a different gain structure.  The thing that matters is gain.....that is what will determine matching.....and you have it.  And the output impedance will only affect frequency response if it is really high....both amps are very, very low.....7 and 15 millioms........so even into 2 ohms there will be NO loss whatsoever.

it is also good that both amps have a high input impedance (200K).....then two of them in parallel is 100K.....still plenty high.....and easy for the preamp to drive.

Only what I write on the internet is true.....he he....I am NEVER WRONG......except when I am....

with my R105/3 even with a 93.5 db sensitivity I still horizontal bi-amped them with a krell kav 300il on top and a B&K 4420 driving the bass. The Blades are a much easier load and the quality of the uniq is miles ahead. IDK how big a room you're trying to pressurize but the Hegel H590 is powerful enough to drive the blades full range to +100 levels in my 17x27x7' basement listening room and with full, hard hitting bass I find I don't need to turn the dial quite so high.