The most basic characteristic of any speaker for many listeners will be the broad tonal balance that it offers. I can very simply characterize the RX1s by saying that they have a broad midrange emphasis, with smooth and extended treble and tight bass of limited extension. This is a sound whose frequency response curve I have characterized in the past as being “n” shaped, to contrast it to a “u” shaped tonal curve in which bass and treble are emphasized (listen to a Bose car audio system to hear a “u” shaped curve). My personal feeling is that “n” shaped curves work better musically, particularly in less expensive gear where sizable tradeoffs are inevitable. But you may feel differently (a quick inspection of rental car audio EQ suggests that the population at large prefers the “u” curve), so be sure to take this bias into account when responding to the tone of my remarks here.
It is important to note that in the standard definition, the mid-range runs from about 200 Hz to 5000 Hz. Almost every instrument has its fundamental tones—all of them—in this region. That makes the midrange of music very important. I was impressed by the RX1 because not only do they slightly highlight this region—and thus they sound very clear and resolved, but they also deliver a level of quality in the midrange that is exemplary. One aspect of this high quality midrange portrayal is smoothness. Within the broad midrange there are many speakers that experience peaks and dips that color the sound of particular instruments. I heard less of this on the RX1 than I do on many speakers under $5000. In addition, the RX1 has a midrange quality that I would describe as having low distortion. I think part of this is due to the dynamic ease with which the RX1 handles midrange transients. Another way of putting this is to say that the RX1 sounds very clear, with high resolution, but without an edge. That makes the RX1 very musical in my mind, because you aren’t constantly getting cues that the sound is reproduced.
In covering the Monitor Audio Silver RX8’s, Chris Martens observed that at times the speaker could seem to be delivering “too much information.” I noticed this far less on the RX1s than he seems to have on the RX8s, and in fact as I indicated above I think the balance of resolution with smoothness is a key admirable quality of the RX1s. There is, however, an area of emphasis in the upper midrange that might trick you into thinking the speaker is too revealing. In fact, to me it sounds like a response peak. This is a relatively mild deviation bump compared to the hills and valleys in many other speakers.
The RX1 handles small-scale dynamic contrasts in a very lively and expressive way—something you’ll appreciate if you like medium and small scale works. When it comes to macrodynamics, the RX1 is limited not so much by it ability to play loudly (it will make your ears hurt if you want), but because it simply doesn’t have the mid- or low-bass punch needed to make some big music sound powerful.
I also really enjoyed the lateral imaging of the RX1. I think a speaker that can get the image “off the box” really helps to convey a sense of a live performance, and the RX1 does this admirably. That said, the RX1 delivers a truncated vertical soundstage. I find that with many small speakers, and the RX1s are included here, the height of images and soundstages seems to stop at about the top of the speaker. This doesn’t happen as much with bigger speakers, though I am at a loss as to why this should be so.
I used the RX1s in a medium sized room (2500 cu. ft.) with two different 25 watt per channel amplifiers (the NAD 320BEE and the Wadia 151 PowerDAC). This amplifier power was adequate in my experience because the RX1 is relatively easy to drive. I do think the tonal balance of the RX1 would suit a smaller room better, because the room resonances would be at higher frequencies to better support the mid-bass region. A speaker with more bass and a different bass balance may not work as well in a small room because it excites the bass modes too much (especially when near a corner as is often required in smaller rooms). I was pleased to see that Monitor provides foam rubber port plugs so that users can fine-tune the speakers/room bass characteristics.
Note that one potential way to transcend limitations of the RX1 while tapping its many strengths is to use the speaker as the heart of a very high performance desktop audio system.