KRK RP8.. I've heard the BX8a are not as accurate... let me see if I can find you the article on this one guys reviews of both of it.
Read this and you will see why KRK is a better choice...
http://studio-central.com/phpbb/viewtopic.php?t=32148
Details
"Well, I've spent quite some time throwing all kinds of sonic material for these two monitors to reproduce and I've observed some significant differences.
The BX8a's gave me the impression of a hi-fi speaker more than a studio monitor. If I were to picture an equalizer setting to match the response the BX8a's give out, it would look like a smile with a dip in the mids. The most noticeable differences between the BX8a's and the RP8's are the highs, and the lows. The highs are overbearing. As much as M-Audio likes to advertise their silk tweeters, the sound they put out is rather unsmooth. My impression of the highs were that they were exaggerated; and on high volumes, can be painful on the ears. On low volumes, the highs were listen-able, but I really felt that it did not accurately represent what the monitors were being fed. The RP8's tweeters had a much smoother sound to them, not harsh, fatiguing, and abrasive like the BX8a's. I felt the RP8's had a better representation of sound with highs than the BX8a's. With the BX8a's, audio such as vocals and acoustic guitar sounded dry and unnatural to me. Light acoustic guitar sounded "tinny" at times because of the sharp highs in the BX8a's. When a vocalist would hit "F's" or "S's" they would sound piercing on the BX8a's, while the RP8's would round them off nicely, and balanced the highs right where they should be for an accurate monitor of this level.
The RP8's really got to shine when it came to the mids. Throwing some naked vocals at these two monitors showed some major differences. The BX8a's lacked in this category. Visualizing a stage with a vocalist, switching from the RP8's to the BX8a's was like hearing that vocalist move back further away on the stage. The mids were present on the BX8a's, but there was no substance in them. The RP8'S had more "breath" in them, and this really showed when running some Jack Johnson through them, as well as songs featuring acoustic wind instruments such as flutes, orchestral stuff etc.
Bass was also an interesting difference. The BX8a's put out much more bass than the RP8's. Kick drums with the BX8a's hit way harder than the RP8's. The BX8a's can really make the floor shake. Unfortunately, the bass is greatly exaggerated and doesn't accurately represent the audio. Sometimes the upper-lows and lower mids would collide with each other and sound muddy, where the RP8's were much better adept at handling it. BX8a's had a more looser, boomier sound, while the RP8's had a tighter, punchier sound to them.
The two are comparable in features. The RP8's have an unbalanced RCA input and HF balance over the BX8a's lack of them. I also felt that the RP8's had a more solid build to them. The rubber surround was an important difference. The surround on the BX8a's was much thinner/looser, while the RP8's had a thicker/tighter surround. I believe that the looser surround is what allows the BX8a's to hit as low as they do, but compensates on accuracy, while the tighter feel of the RP8's give a more accurate response of the sound. "
I plan on getting these monitors as soon as I get the money.