Dear Shane:
It appears from your thread that you are home demo'ing various amps in your system, which is the hands down best way to demo equipment. Be very careful (i.e., skeptical) about other people's experiences with various amps in systems other than your own, as the amp/speaker interface is highly component-dependent -- how, for example, a VTL 450 performs on someone else's speakers in someone else's system is fairly well irrelevant to how it will work with your electronics running your Mahlers. The only way to know is to try a fully broken-in version of the amp in your system, the only variables introduced to the comparison being adjustments to speaker placement so as to correct for what the amps do to soundstaging and power delivery, and, being open to using speaker cables that are known to partner particularly well with the amp (the amp / speaker cable interface is more important than the speaker cable / speaker interface, incidentally*).
I use Mahlers in my second system and have tried three amps with them. A Bryston 4B-ST was fine. The VAC Renaissance 140/140's monoblocks that I use in my main system were much better (and the bass was fine, incidentally). The best match was Rowland Model 6 monoblocks with batteries, which had most of the bloom, all of the transparency and better bass control than the VAC's. The Rowlands were the most dynamic and really took a hold of all of those 10" woofers.
If you are committed to running tube amps with your Mahlers, I strongly suggest that you investigate the CAT amps, especially the monoblock versions. While they are limited to 100 (JL-1) or 200 watts (JL-3) per channel, the quality of the output transformers on the CAT's is generally known to be the highest in the industry, meaning that they really nail the voltage-to-current conversion such that they can handle tough-to-drive or tough-to-control speakers in a way that tube amps with much higher wattage ratings cannot touch. People misunderstand what is important for getting power and control out of a tube amp -- if the amp does not have great output transformers, all of the watts in the world will be wasted. Here is a thread that addresses the issue of tube amps and power in the context of the very hard to drive mbl omnidirectional speakers:
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1099200096&openfrom&1&4#1
There are very, very few tube amps that are going to do the job on Mahlers, and you even have to be careful with solid-state amps (Tony Cordesman, in his review of the Mahlers for Audio, reported that his monstrous Pass 600's were not nearly as good at controlling the Mahlers' bass as Krell FPB 300 monoblocks). Extensive home demo'ing is definitely the way to go with these speakers.
*That said, I did a lot of research regarding speaker cables for the Mahlers because of the hard-to-control woofers, and Vienna Acoustic's U.S. distributor, Sumiko, directed me to Kimber Monacle. I bought Kimber Select 3033, which is a step up in the Kimber line from Monacle, and it really helped to make things fall into place. I also borrowed 3038, the all-silver version, from my main system to run with the Mahlers for awhile, and they were supurb.
It appears from your thread that you are home demo'ing various amps in your system, which is the hands down best way to demo equipment. Be very careful (i.e., skeptical) about other people's experiences with various amps in systems other than your own, as the amp/speaker interface is highly component-dependent -- how, for example, a VTL 450 performs on someone else's speakers in someone else's system is fairly well irrelevant to how it will work with your electronics running your Mahlers. The only way to know is to try a fully broken-in version of the amp in your system, the only variables introduced to the comparison being adjustments to speaker placement so as to correct for what the amps do to soundstaging and power delivery, and, being open to using speaker cables that are known to partner particularly well with the amp (the amp / speaker cable interface is more important than the speaker cable / speaker interface, incidentally*).
I use Mahlers in my second system and have tried three amps with them. A Bryston 4B-ST was fine. The VAC Renaissance 140/140's monoblocks that I use in my main system were much better (and the bass was fine, incidentally). The best match was Rowland Model 6 monoblocks with batteries, which had most of the bloom, all of the transparency and better bass control than the VAC's. The Rowlands were the most dynamic and really took a hold of all of those 10" woofers.
If you are committed to running tube amps with your Mahlers, I strongly suggest that you investigate the CAT amps, especially the monoblock versions. While they are limited to 100 (JL-1) or 200 watts (JL-3) per channel, the quality of the output transformers on the CAT's is generally known to be the highest in the industry, meaning that they really nail the voltage-to-current conversion such that they can handle tough-to-drive or tough-to-control speakers in a way that tube amps with much higher wattage ratings cannot touch. People misunderstand what is important for getting power and control out of a tube amp -- if the amp does not have great output transformers, all of the watts in the world will be wasted. Here is a thread that addresses the issue of tube amps and power in the context of the very hard to drive mbl omnidirectional speakers:
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1099200096&openfrom&1&4#1
There are very, very few tube amps that are going to do the job on Mahlers, and you even have to be careful with solid-state amps (Tony Cordesman, in his review of the Mahlers for Audio, reported that his monstrous Pass 600's were not nearly as good at controlling the Mahlers' bass as Krell FPB 300 monoblocks). Extensive home demo'ing is definitely the way to go with these speakers.
*That said, I did a lot of research regarding speaker cables for the Mahlers because of the hard-to-control woofers, and Vienna Acoustic's U.S. distributor, Sumiko, directed me to Kimber Monacle. I bought Kimber Select 3033, which is a step up in the Kimber line from Monacle, and it really helped to make things fall into place. I also borrowed 3038, the all-silver version, from my main system to run with the Mahlers for awhile, and they were supurb.