I get all the discussion about amps sounding the same, and for the most part, I agree. In general, I think Dennis Erskine nails it when he says that amps should not be "tone controls." However, I'll add the caveat that amps need to remain within their own performance envelope with respect to distortion and clipping.
Therefore, if the OP is hearing "brightness", it begs the question: Is he using his amp within its' performance envelope? Let's look at the amps in the Sony STR DH820:
(8Ohms 1kHz) THD : 1%
(8Ohms 20-20kHz) THD : 0.09%
8Ohms 1kHz : 110W+110W
8Ohms 20-20kHz : 100W + 100W
Output Power (JEITA 10%)/ Rated Output Power(0.09% 20Hz-20kHz 4Ohm) : 10%
Output Power (JEITA 10%)/Rated Output Power(0.09% 20Hz-20kHz 8Ohm) : 150W
Total : 945W (135W/ch x 7 (8?, 1kHz, 0.05% THD))
4 Ohm/8 Ohm Switching : 8 Ohm only
Advanced Auto Volume : Yes
Analog Direct : Yes
Bi-AMP : Yes
Digital Legato Linear : Yes
Number of amp. channels : 7ch (Sub must be self powered)
Sound Optimizer : Yes
Speaker Selector : A/B/ A+B
Speaker Terminal : Screw
Sub Woofer X' Over : 17 points (40-200Hz)
So, we have an amp that is specified for 8 Ohm loads, (i.e., can't deliver enough current to drive 4 Ohm loads), and a power supply that causes the spec's to change depending on the frequency(s) driven, (i.e., 110 watts @1 Khz, 100 watts 20Hz - 20kHz, which is another indication of a marginally inadequate power supply.)
Now, let's look at the speakers:
Drive units (1) 1" aluminium dome tweeter
(2) 6.5" CPC aluminium mid/bass
Frequency response 38Hz - 22kHz
Nominal impedance 4 - 8 Ohms
Crossover Damped 2nd order with DVP
Recommended amplifier power 15-150 Watts
Magnetically shielded within 50mm of cabinet
Weight 17.3kg (38.1lbs)
Dimensions (h x w x d) 950 x 205 x 298mm
38 x 8.2 x 11.9"
Available Finishes Dark Walnut, Black
(Actually, it's much worse than that: S&V measured the speaker at 3.3 to 6 Ohms
with a sensitivity of 83 dB
So, we now have a low impedance speaker, with low sensitivity, being driven by an amp not capable of driving low impedance speakers and with a limited current delivery capability. That sounds (PI) like a recipe for clipping, compression and distortion.
Something else the OP says plays into this:
...but it just sounds to bright and not punchie enough on 2 channel stereo. dd sounds fine tho with the sub running.
Most ported speakers show an impedance dip just above the port tune, which in this case is about 35 Hz. If he uses the sub with DD, (and sets a typical crossover of 80 Hz), he eliminates, (or more correctly, greatly reduces), the impact of the impedance dip, AND he reduces the power demands on the amps significantly. This would reduce the clipping, compression and distortion significantly. Hence why "dd sounds fine tho with the sub running."
Bottom line, IMO, the "brightness" and "lack of punchiness" he's hearing is probably the amps clipping. He's not using the right amps for his low impedance, power hungry speakers, and he probably *would* benefit from an amplifier upgrade. Unfortunately, his Sony receiver doesn't seem to have preamp outputs, so he would have no way to upgrade the amp section, short of getting a new receiver.
garthvader86, if you decide to upgrade your receiver, look for a receiver capable of driving low impedance loads. In the Amplifier Specifications, look for a spec for power delivery into 4 Ohm loads. If there is no such spec, the receiver can't drive 4 Ohm speakers. The ideal spec would be a doubling of the 8 Ohm spec, but don't expect to find that. However look for at least a 50% wattage increase into 4 Ohms over the 8 Ohm spec.