Just played my first gig with the Aguilar Tone Hammer last night and wow - it was great. So, I thought I'd pass along my observations in case they might help someone else on a similar tone quest. First, my tone goals. I'm looking for a somewhat dirty hard rock sound. Narrowly scooped around 500Hz, but with punchy low mids between 100 and 400 Hz to cut through, and nice throaty high mids around 700 to 1000 Hz to carry sweetness and make effects audible. The exact frequencies depend on the room and what parts of the spectrum bandmates are using. My gold standard would be a vintage Ampeg SVT and 8x10 sealed cabinet, buy I need something way more portable and I never need that much volume. I should also say I don't care what an amp sounds like in a music store or sitting in a room by myself. I need to hear it live at a gig to know what it's going to do at a gig. Next, the gear used with the various heads. I ran these through a pair of Markbass Traveler 102p cabinets, stacked vertically. Tweeters dialed all the way off. Signal chain is: Ibanez SR-535 (stock Bartolini pre and Bart MK1 pickups) -> Markbass Compressore set pretty squishy -> amplifier input; FX send -> multieffects pedal -> Tech 21 Sansamp Para Driver DI -> FX return Next the observations. Eden WT550 Strengths: Lots of flexible features. trim knob for the DI signal. Runs well at 2 ohms. Runs well with no speaker load. Good sounding builtin compressor. 3 bands of parametric EQ to fine-tune midrange. The tone is sophisticated but warm. The 12AX7 in the Eden's pre is not just there for show. The tone is clear and natural. I would choose it for an acoustic instrument or smooth jazz. Eden WT550 Weaknesses: I'm on my third Chinese-made one. Eden #1 smoked 2 months after I bought it new in 2010. Eden replaced it under warranty, and the replacement was finicky about power. The thermal protect would kick in at 2 gigs out of 3. I bought a different head just so I could keep working. After almost a year of that, Eden took it back for repair. Eden #2 worked well for about a year, then failed in the middle of a gig. Eden replaced it again, which shows really above-and-beyond customer service. Eden #3 is a couple of months old and shows no signs of trouble. I tried to sell it, but when I told the story of why it was for sale people seemed to lose interest, so Eden #3 will have a home in my band room and I will take the lightweight heads out gigging. Streamliner 600 Strengths: Very reliable. Has never given me any trouble. Nice tubey feel. I don't know how they did it, but I swear I hear a tube power section sagging in there. Very punchy low mids with the freq. selector at 250Hz. Cuts through nicely. Lightweight at 6 lbs. Streamliner 600 Weaknesses: The high mids and highs are not emphasized. I would use this amp for motown and oldies genres. I like grind and effects, however, and the STM600 just doesn't carry these well IMO. The controls on this are famously interdependent; you turn the gain up to a little dirt and you get a lowpass filter effect. Sure, too much treble makes dirt sound harsh, but the STM600's cutoff frequency is too low for my taste. I want to dial it in myself. The single midrange control is switchable between 3 frequencies, but it needs to stay on 250 Hz for the punch. The suppression of highs & high mids bugged me enough that I started running the Sansamp straight into the effects return, bypassing the Streamliner's preamp completely. It sound nice as a power amp, FWIW. Aguilar Tone Hammer: I just got this amp and gigged it once last night and am really excited about it, I think for good reason. I'll try to stay objective. Aguilar Tone Hammer Strengths: Tone, Tone, Tone. The EQ section is powerful. You turn the knobs through their range and it sounds like a wah pedal. With the parametric mid frequency down around 100 or 200 Hz and boosted it gets nice and punchy. The Streamliner is punchier, but the TH500 is still very good. The treble control opens up enough to let my high mids through. I can hear my effects clearly! It does not get Hi-Fi sparkly, but I'm not looking for that. I turned my tweets off anyway. The drive and gain can give it some nice harmonic content that I hear as "character" in the mix, i.e. I can hear details in the tone and articulation in the notes that don't come through with the Streamliner. Doesn't go super low or super high. For a lot of folks that may be a weakness, but for me, in practical terms, it's a strength. I have rarely played a room that didn't resonate lows and subs in an ugly way. I always cut lows or leave them flat. That's one of the things that's different at a gig versus a music store. So, the lack of low frequency extension for me means I don't have to fight mud... goody. I'm glad the super highs aren't there because as previously noted they can harsh out my dirt and also because I'm not the virtuoso that controls all fret and string noise with hands alone. So, the absence of 4kHz is a favor to me Plenty of power - Though only rated at 500 watts, the master volume sits much lower than the other two heads for the same loudness. DI and FX loop are on the front panel. Nice touch, makes setup easy. Lightweight at under 5 lbs. Aguilar Tone Hammer 500 Weaknesses: The drive and gain aren't really usable to get real dirt. When pushed to distortion levels they sound kind of plasticky and solid-state. The Streamliner has nicer natural distortion but I find the best dirt in my Sansamp pedal. Other notes: Compared to a real SVT+8x10 my rig is in the same tonal space and sounds good. The power section is too quick and it doesn't hit you in the chest as well as a real SVT rig. I use the Sansamp to get my tone color and dirt. Its parametric is set to boost high mids. The TH500's parametric is set to boost low mids. The Sansamp's drive is set to just past the edge of audible distortion. The TH500's drive & gain are set to where they just sweeten the harmonics without adding any more grit. The Sansamp and TH500 pair well together. This rig will never "wump" like an SVT and 8x10. I attribute that mostly to the cabs. A pair of ported 2x10s won't naturally sound as tight down low as a sealed 8x10. Also, the Markbass 102ps are a compromise. For a cab that small and that light, it's amazing they can handle 400w each and sound as great as they do at only 30-ish lbs each. A single 102p sounds wimpy to my ear. Somehow when you stack two of them they grow muscles and start to sound pretty good. I don't know why. On the other hand, you couldn't fit the SVT rig in this: Sorry about the long post, I hope it helps somebody with similar tone goals to get there without spending as much time and money as I have (so far). Disclaimer: As always, IMO and IME and YMMV. Kool-aid for sale down the street. I'll take a beer.