Thank you, everyone, for your replies so far. Some comments and answers to your questions:
I searched for bench tests on Marantz receiver pre-outs and found a few from Audioholics that test this, however, I'm a little confused by what I've read.
For example, in this review (
https://www.audioholics.com/av-receiver-reviews/marantz-sr8012-receiver/marantz-sr8012-bench-tests) Gene mentions that the Marantz SR8012 is capable of 4.5Vrms, but in his testing, he couldn't get more than 1.2Vrms. It sounds like the test signal was too strong to get more than 1.2, but with real-world material you can get 4.5. However, I'm not sure how he determined this.
In this review (
https://www.audioholics.com/av-receiver-reviews/marantz-sr6004-1/sr6004-measurements) Gene says, "With 0dBFS in, the SR6004 was able to output a whopping 7Vpp unclipped (<.1%THD +N) or 2.49Vrms." So does this mean the SR6004 was capable of outputting 2.49Vrms from it's pre-outs?
If I'm understanding this correctly, then if the pre-outs in my Marantz receiver perform similarly to these models, then I should have no problem outputting 1.6Vrms to fully power the Monoprice amp with this receiver?
Regarding why I think I need an amp for these speakers, I'm not certain that I do. However, that seems to be what everyone says. For example, in the various reviews I've read on these speakers (e.g. Stereophile, Audio Science Review just to name a few), they point out that even though these speakers are spec'd at 8 ohms nominal, they fall down to 4 ohms for much of the frequency range, so they say an amp is necessary because of this. My Marantz receiver is also not spec'd to be able to drive 4 ohm speakers (only 6 to 8 ohms). Most people on the Revel owners thread on AVS forum seem to suggest an amp is the way to go as well.
I've only had these speakers for a week. So far, they sound fantastic with my Marantz receiver. I'd say they are the best sounding speakers I have ever heard. My last two sets of speakers were GoldenEar Triton Twos and Paradigm Studio 20s. I did a detailed A-B comparison between Revels and GoldenEars, and the Revels definitely sound better. I'm surprised how much better I think they sound. I thought the differences would be smaller since I thought the Triton Twos were quite good (however, next to the Revels, not so much).
My listening room is approx. 3,000 cubic feet. My speakers are about 10 feet away from me. I also have two PSA V1500 subs, which I cross over at 80hz, so I would think those take a lot of the load off of my receiver.
I like to listen loud. I like all sorts of music, but mostly listen to heavy stuff (like Tool). Using a UMIK at my listening seat, I usually listen to my music in the high 80s to mid 90s. With the Revels, I usually have my receiver volume set around -20 to -15 and this delivers high 80s to mid 90s db at the listening seat. If I turn it up louder than -15, it starts to sound harsh. Whether that's due to distortion being introduced, or just having the volume too high for my ears, I don't know. However, I'd like to make sure I have enough headroom for dynamic peaks without worrying that I might be sending a clipped signal to these speakers.
Any feedback would be appreciated!