Marantz av7005 vs av8801 vs Theta Casablanca

In my experience, the Theta stuff is designed to be very fast/clean.  It is conventional op amp I/V after the dac with no Class A or waveform smoothing warmth.  I suspect it is a bad match to your Emotiva amps, which are very fast/neutral.  The Theta will likely do better with a very warm or Class A based amp.

the AV8801, on the other hand, is a very warm/slow sonic signature. I suspect this is the better option in your situation, but you might feel it is too warm/slow.  You could try some silver internects and/or speaker wire if you thought it was still too warm.  

I don’t know that the Marantz has a Class A analog stage.  I do know that the AV7005 (and their other processors) will have a fully discrete analog output stage.  They also typically use a slow slew rate op amp for the DAC I/V stage.  This give the sound more warmth and a slight rolloff in high frequency response.

before you start looking at tube amps, I would upgrade the fuses in the Emotiva to Isoclean fuses.  There are two 10A small 5mm x 20mm fuses accessible from a bottom panel.  There are also two 1A small 5mm x 20mm accessable be removing the top cover.  The Isoclean will remove a lot of the harshness and help warm up the sound a bit.

the older Marantz equipment was very warm/slow.  If you feel it is too slow, you can try looking for a Marantz AV7702, which uses the newer HDAM circuits that are faster slew rate.

I have heard the Emotiva Class A mode. It is not a super warm/rich sound.  It keeps the general Emotiva fast/neutral sonic signature, but it smooths out the sound a bit, making it a tiny bit softer and laid back.  It is very subtle.  When the Emotiva Class A switch is off, the sound is somewhat bright/harsh.  The Emotiva circuit is a compromise on this, so when you have Class A switched off, there is waveform crossover distortion because the circuit is not designed strictly for Class AB.

i never recommend a bi-amp setup unless you are running an active crossover or have multiple active full range outputs (such as on the Classe CP800 preamp).  The dual output bi-amp configuration on these processors almost always degrades sound quality.  It sends full range on the normal left/right outputs.  However, it looks at the actual waveform used by this and compares it to the original by using an opamp circuit and then subtracts the “used frequencies” from the full range signal and then outputs this “converted” signal to the upper bi-amp outputs.  In my experience, it is always best not to bi-amp at all and just focus on using the best amps you can.

Ah sorry, I mistyped.  I see you got the av8801.  This still has the older Marantz circuits that are a bit slower/warmer than the newer AV8802A or AV7702 processors.  But if you like the sound, I would keep it for now.  :)

One of the things I really like about the av8801 and av8802 is that Marantz put in a very large power supply for this processor, so the sound will be very full and have a lot of muscle in the bass and midbass.  

Sorry, that message posted before I was done.  I don’t know much about av8801 configuration quirks.  Probably best just to read the manual and try to work from there.  There are definitely some processors that will not do bass management (i.e. subwoofer output) for 2-channel music.  My old Krell HTS had that quirk.  However, the new Krell S1200 and Bryston processors will enable sub for 2 channel music.  If you are using an analog source (like turntable or external DAC), the Marantz could be acting as a pass through preamp, in which it does no conversion to digital for bass management.

Good choice working with an active crossover (like I mentioned before).  I have worked with Ashley pro equipment.  I’m assume you are looking at something like the XR-1001 crossover.  The Ashley stuff has a tube like bloom to the sound.  I believe part of the reason is that Ashley’s internal power supply runs at the bare edge limit of the op amps (+/-18V).   If you want something with a flatter more neutral response, look at a used Rane AC22 crossover.  Rane power supply runs at a more conservative +/-15V.

if you are willing to spend the money, the Bryston 10B is probably the best.  Fully discrete Class A analog circuits with big linear power supply.  Make sure you know which version.  Some versions have RCA, some XLR.  The Bryston will have the most resolution/transparency compared to Rane or Ashley.

if you can get the Emotiva and Marantz to sound good, you may not feel the need to bixamp.

There is nothing that you can do easily with the Emotiva other than a fuse upgrade.  I had XPA-1 Gen 1 in my system.  Currently, I am running with XPR-1 and XPA-1L amps.  Both of these amp versions use two fuses (such as 2 x 4A for the XPAx1L).   I found that my Emotiva amps sounded the best with one Isoclean fuse and one Furutech fuse.  It was an excellent balance of clarity and warmth.  I found that running two Isoclean was just too warm/slow.  Running with two Furutech was too thin/lean.  I am using a really fast high resolution Krell processor (not warm at all). In your situation, it might be that two Furutech would sound best because the Marantz is so warm/slow.  The type of interconnects and speaker cable and power cables could also affect the sound.

fuses are used to help “tune” your system to get further towards the type of sound you want.  I just gave you my two preferred fuses.  You can start however you like.  If you do get fuses, make sure to burn in before making any decisions.  100 hours for the Isoclean.  With Furutech, you need about 240 hours before it calms down (because of the rhodium).

Oh, you could do fuse upgrade in your Marantz AV8801 as well, if you wish. For this, I would recommend a 2A Furutech for the most speed and resolution. I don’t know the physical size, as I think the fuse is inside somewhere.

if you are cost conscious and don’t want to waste money experimenting with multiple Furutech/Isoclean fuse combinations, you could try the generic PADIS fuses for the Emotiva amps. The Isoclean are very warm, but very inviting in the sound.  There is definitely a magic with the Isoclean. The Furutech are extremely high resolution and transparent. The PADIS are somewhat in between.

as far as the Furman goes, I don’t know. Usually, people say to plug the larger amps directly into the wall, but others have had success with power conditioner. Best suggestion is to try it both ways and see if the Furman restricts the sound. Plugging into the wall could give more current which would be more muscle in the bass and the instruments would hit with more authority.

Theta upgrade will be extremely expensive.  You are probably looking at $4,000 to $7,000 to upgrade to latest, depending on which DSP version and DAC boards you need.  If you want 9.1, it's probably over $10k for sure.

Based on all that I have read, the general consensus would be that the 8802 is faster and more detailed than the 8801 (more attack and clarity).  Marantz engineered a slightly faster slew rate on their analog circuits for the 8802 (using the new HDAM circuit).  The older 8801 will be slower/warmer sounding.