Wow - you couldn't pick two more different speakers both in terms of sound and driveability.
The Ruby has very low sensitivity (around 84dB if memory serves me) and really needs a solid amplifier to bring out their best - staggering bass from such a small enclosure and a very forward, punchy and dynamic sound.
The Credenza has sensitivity of over 100dB and a less detailed presentation though also quite forward and very musical. They sound great with tube amplification requiring very little power to get them singing.
For the Virtue 2, for me it's no contest - the Zu's would definitely be the better match. If you had a more powerful amp - say 100 watts/8ohms minimum, then it would be a different story. For your music tastes, I think you'd really enjoy the power and drive of the M&D's.
The Ruby has very low sensitivity (around 84dB if memory serves me) and really needs a solid amplifier to bring out their best - staggering bass from such a small enclosure and a very forward, punchy and dynamic sound.
The Credenza has sensitivity of over 100dB and a less detailed presentation though also quite forward and very musical. They sound great with tube amplification requiring very little power to get them singing.
For the Virtue 2, for me it's no contest - the Zu's would definitely be the better match. If you had a more powerful amp - say 100 watts/8ohms minimum, then it would be a different story. For your music tastes, I think you'd really enjoy the power and drive of the M&D's.