Originally Posted by AcuDefTechGuy
Even if you eventually change your entire system, it's good to do it one step at a time.
I also think your Marantz is fine. I would not change it unless it has issues driving your speakers, which I doubt.
The Marantz 6007 can output 153WPC x 2Ch into 8 ohms, 196WPC x 2Ch into 4 ohms
, and 92WPC x 5Ch into 8 ohms.
It is similar to the Denon 3312/3313/X4000. I have used the Denon 3312 to power a pair of B&W 802D2, KEF 201/2, ATC SCM7, Focal 826v, Dynaudio X32, Philharmonic 3. No power problems at all. So I would not worry.
So just get high quality dual subs first. Then next step would be the speakers if you feel the upgrade fever.
For speakers, in most rooms, don't even worry about high efficiency (HE) vs. low efficiency. For extremely large rooms, HE speakers makes sense. But most of us have rooms not larger than 20' x 20', so no big deal. HE doesn't hurt, but just not an important factor.
Then you have the speaker measurements, particularly the on-axis frequency response and off-axis frequency response. Some double-blinded studies (Floyd, Olive, Harman) show that "most" people (not all people) prefer speakers with flat on-axis and smooth off-axis. BTW, this is also a requirement for THX Ultra2 certification of speakers - flat on-axis, smooth off-axis. THX also requires the speakers to be able to play to THX reference SPL volume, but for most rooms under 20' x 20', this won't be a problem for most speakers.
Obviously, theory and measurement is one thing. But how the speakers actually sound to you in your room is the most important thing.
And then you have other factors like aesthetic, price, pro review, peer review. Is peer review important to you? Do you buy speakers based on a few people's approval?
So you can do research and then ask yourself what is important to you. Is speaker measurement important to you? If it is, then don't buy speakers with poor measurement or no measurement at all.
Let's say it came down to 2 speakers - A & B. Both sound equally great to YOUR EARS, both are the same price and equally in every way except one. Speaker A has perfect speaker measurement, while speaker B has poor speaker measurement or no measurement at all.
Which speaker would you buy?
And realize that many of us have upgraded our systems many times over. So take your time and do a lot of research. Then do some more research unless you want to be like us and feel like upgrading again next year.